Michelin Truck Tire Service Manual

Michelin® Truck Tire Service Manual MICHELIN QUALITY STATEMENT

The Company exists because of our Customer: our true boss. Our goals at all times are: To offer the Customer the best tire at the best price in each segment of the market, To set the standard in Quality of service. Each employee is expected to actively participate in our progress toward Total Quality by: Anticipating and satisfying Customers' expectations, Achieving Right the First Time in all activities, Continuously improving the Quality of products and services.

E. Michelin R. Zingraff

September 1996 INTRODUCTION Read this manual carefully - it is important for the SAFE operation and servicing of your tires.

The purpose of this manual is to provide you, the Michelin® Truck Tire customer, with some useful information to help you obtain maximized performance and cost per mile. Your Michelin radial tires are a significant investment and should be protected like any other investment. This manual will show you how to do this by increasing your knowledge of tires regarding their selection, vehicle characteristics that affect performance, maintenance, and extending tire life through repair and retreading. For complete tire specifications, refer to application data books, contact your local Michelin Representative, or refer to the Michelin web site: www.michelintruck.com.

For additional information consult the following manuals: Michelin Data Book (Passenger Tire and Light Truck Tire) ...... MDL41780 Michelin Truck Tire, Retreads and Commercial Light Truck Tire Data Book ...... MWL40731 BFGoodrich Commercial Truck Tires Data Book ...... BWL42029 Tires for Material Handling ...... MEL41637 Earthmover and Industrial Tire Reference ...... MEL41736 Earthmover and Industrial Data Book ...... MEL40017 Michelin Commercial Truck Tire Nail Hole Radial Tire Repair Manual ...... MWT40163 Michelin MRT Tread Width Informational Guide ...... MYT41805 Crown / Sidewall Repair Template ...... MWT40192 Truck Tire Limited Warranty and Driver’s Manual ...... MWE40021 BFGoodrich® Truck Tire Warranty ...... BMW40844 Passenger and Light Truck - Michelin Complete Warranty ...... MDW41156 Recreational Vehicle Tire Guide ...... MDL40660 Michelin Agricultural Tire Data Book ...... MUT41305 BFGoodrich Agricultural Tire Data Book ...... BUT21140

Technical Bulletins: www.michelintruck.com

CDs: MICHELIN SCRAP TIRE CODING CD ...... MWP42396 PLNA TECHNICAL VIDEOS CD#1 ...... MWP42398 — Fundamentals of Tire Wear — Runflat - Full Term Pinch Shock Impact Damage — The Critical Factor - Truck Blow Out PLNA TECHNICAL VIDEOS CD#2 ...... MWP42399 — ATTACC PLUS Vehicle Measurement Training — Runout & Match Mounting; Scrap Tire Analysis — What Every RV Owner Should Know About Tires PLNA TECHNICAL VIDEOS CD#3 ...... MWP42435 — Proper New Tire Mounting — Troubleshooting Vibration X ONE® TECHNICAL VIDEOS CD ...... MWP42397 X ONE PRESENTATION ...... MWV42737

To obtain copies of these manuals, CDs/DVDs and videos contact your Michelin Sales Representative or contact Promotional Fulfillment Center at 1-800-677-3322, Option #2 (Monday through Friday, 9 a.m. to 6 p.m. Eastern Time). DVDs: ENGINEERING SUPPORT TECHNICAL VIDEOS 2004 ...... MWP42662 TECHNICAL VIDEOS - 2004.1 TECHNICAL VIDEOS - 2004.2 — ATTACC PLUS — How Tires Are Made — Fundamentals of Tire Wear — The Critical Factor - Truck Version — Run Out and Match Mounting — X One® vs Duals Controllability — Scrap Tire Analysis — How to Handle a Blowout — What Every RV Owner Should Know About Tires — Mounting the X One — New Tire Mounting — X One Coast Downs — Troubleshooting Vibration Complaints — Laurens Proving Grounds — Mounting Two New Tires X ONE TIRES VS. DUALS ON A DOLLY ...... MWV42823

Videos: ATTACC PLUS VIDEO - VEHICLE MEASUREMENT TRAINING ...... MWV41200 CRITICAL FACTOR - SCHOOL BUS VIDEO ...... MWV42336 CRITICAL FACTOR - TRUCK VIDEO ...... MWV41415 CRITICAL FACTOR LOOP FOR TRUCKSTOPS ...... MWV41488 EXPLORING THE EDGE - TRUCK VIDEO ...... MWV41826 FUNDAMENTALS OF TIRE WEAR VIDEO ...... MWV41504 MICHELIN KEEPS YOU ROLLING VIDEO ...... MWV41414 NO COMPROMISE VIDEO ...... MWV41417 PRE-TRIP INSPECTION VIDEO ...... MWV41416 PROPER NEW TIRE MOUNTING VIDEO ...... MWV42433 RADIAL RUNOUT AND MATCH MOUNTING VIDEO ...... MWV41721 RV VIDEO - “WHAT EVERY RV OWNER SHOULD KNOW” ...... MWV42019 SCRAP TIRE ANALYSIS VIDEO ...... MWV41925 TIRE PRESSURE SAFETY INSPECTOR VIDEO ...... MWV41418 TROUBLESHOOTING VIBRATION VIDEO ...... MWV42434 X ONE MOUNTING & DISMOUNTING VIDEO ...... MWV42085 X ONE SINGLE TIRE CONCEPT (RAPID LOSS OF AIR) VIDEO ...... MWV42091

Industry Contacts and Publications: TIA (Tire Industry Association) - Formerly ITRA and TANA www.tireindustry.org. Commercial Tire Service Manual OSHA (Occupational Safety and Health Administration) www.osha.gov Safety Standard No. 29 CFR, Part 1910.177 TRIB (Tire Retread Information Bureau) www.retread.org RMA (Rubber Manufacturers Association) www.rma.org Care and Service of Truck and Light Truck Tires Inspection Procedures for Potential Zipper Ruptures in Steel Cord Radial Medium and Light Duty Truck Tires (TISB 33, Number 2) TMC (The Technology and Maintenance Council) www.truckline.com Recommended Engineering Practices Manual TMC RP 214B Tire/Wheel End Balance and Runout TMC RP 216 Radial Tire Conditions Analysis Guide TMC RP 219 Radial Tire Conditions and Causes: A Guide to Wear Pattern Analysis TMC RP 222A Users Guide to Wheels and Rims TMC RP 642 Total Vehicle Alignment ...... MWL41875 TMC RP 643 Air-Ride Suspension Maintenance Guidelines TABLE OF CONTENTS

SECTION ONE – TIRE SELECTION ...... 1 - 12 Why Radial? ...... 1 Why Michelin? ...... 2 - 3 Which Michelin® Tire? ...... 4 - 5 Determining Michelin Tire Size...... 6 - 10 Truck Type by Weight Class ...... 11 - 12

SECTION TWO – MOUNTING THE TIRE ...... 13 - 20 General Instructions for Tubeless Tire Mounting/Demounting ...... 13 - 14 Mounting the Tire ...... 15 - 17 Tubeless Tire Mounting/Demounting ...... 17 - 18 Mounting the Assembly on the Vehicle ...... 19 - 20

SECTION THREE – EXTENDING TIRE LIFE ...... 21 - 36 Maintaining the Tire ...... 21 - 26 Maintaining the Vehicle ...... 27 - 34 Quick Checks for Front Suspension Faults ...... 35 Quick Checks for Rear Suspension Faults ...... 36 Quick Checks for Trailer System Faults ...... 36

SECTION FOUR – X ONE® ...... 37 - 40

SECTION FIVE – REPAIRS ...... 41 - 46 Repairs ...... 41 Measuring Damages ...... 42 Repair Limits ...... 42 - 43 Puncture Repairs ...... 44 - 46

SECTION SIX – RETREADING ...... 47 - 49

SECTION SEVEN – COST ANALYSIS ...... 50 - 51 Cost Analysis ...... 50 Fuel Savings ...... 51

SECTION EIGHT – TUBE TYPE ...... 52 - 56

SECTION NINE – APPENDIX ...... 57 - 74 General Information ...... 57 - 59 Units of Measurement ...... 57 Load Range/Ply Rating ...... 57 Speed Symbol ...... 57 Pressure Unit Conversion ...... 57 Approximate Weight of Materials ...... 58 Load Index ...... 59 Vehicle Alignment Field Method – ATTACC PLUS system ...... 60 - 61 Casing Management ...... 62 - 63 Cold Climate Pressure Correction Data ...... 64 Conversion tables (standard – metric – degrees) ...... 65 Critical Six Fundamentals ...... 65 DOT Sidewall Markings ...... 66 Hub and Stud Piloted Wheel Types ...... 67 - 68 RPM Calculations ...... 69 Runout and Vibration Diagnosis ...... 70 - 71 Toe Measurement – Field Method ...... 72 Tire Damage – Effect and Cause / Scrap Inspection Form ...... 73 - 74

INDEX ...... 75 Section One TIRE SELECTION Section One WHY RADIAL? TIRE SELECTION

As the diagrams demonstrate, the Michelin® tire 2. Another innovation is the belt around the cas- concept helps improve the tire’s highway perfor- ing that braces and stabilizes the tread, helping mance. Under the same pressure and load condi- to improve contact between vehicle and road tions, the Michelin tire offers more fuel and cost- and reduce unwanted movement in the tread- efficiency, better road handling, increased comfort, road contact area. reduced downtime and repairability. 3. In other words, the two major features are its Fuel Efficiency: The steel braced tread and radial radial wall and tread bracing belts, which per- casing result in less rolling resistance and less heat form their functions quasi-independently. buildup from internal friction when the tire is in motion. This combination translates into lower fuel bills and extended casing life.

Lower Cost-Per-Mile: The radial construction of the Michelin tire reduces friction and heat buildup inside the tire, retarding casing deteriora- tion. This, combined with the radials proven tread life advantages, helps provide a lower overall cost/mile.

In addition, the retreadability of the Michelin truck tire is a significant cost saver.

Road Handling: A Michelin radial tire has sure- footed grip on the road; its footprint is solid; its sidewalls and its tread work independently, and its contact area on the ground is not distorted. Better road handling means greater dependability and performance.

Comfort: By its construction, a radial tire deflects THE MICHELIN® X ONE® RADIAL under load and this flexibility helps to cushion TIRE shocks and give a smoother ride. The Michelin® X One® family of truck tires is Reduced Down Time: The steel belts help pro- designed to replace dual assemblies on drive and tect against punctures. trailer positions of tandem over-the-road vehicles. See the X One® tire section (Page 37) for details on Repairability: Proper repairs within specifications mounting procedures and air pressure mainte- can place the tire back into service, lowering cost. nance practices.

THE MICHELIN® RADIAL

1. The body ply cords in a Michelin casing are laid radially, a design feature that makes the tire’s walls extremely flexible. These supple walls “give” under load, absorbing unevenness in the road surface. Michelin, therefore, introduced a new era in driving comfort. 1 TIRE SELECTION Section One WHY MICHELIN? EXPERIENCE, QUALITY, INTEGRITY — NO COMPROMISE

EXPERIENCE ufacturing process, from raw materials to finished product, production standards and requirements Michelin. It’s a name known around the world are constantly verified. for high quality tires and technological innovation. Michelin’s North American facilities have grown considerably since the first plants opened in Michelin has been earning that reputation for the early 1970s. Today, all plants incorporate more than a century now, making radial tires for Michelin’s latest technological developments and almost every vehicle on the road — and in the air. highly automated production processes. Michelin® tires are designed, produced and Testing plays an important role in assuring marketed by a worldwide work force of over Michelin quality. That’s why Michelin operates the 125,000 employees, with approximately 74 manu- Laurens Proving Ground in South Carolina. Opened facturing plants. In North America, Michelin oper- in 1976, the facility today includes a wide range of ates 21 plants in 17 locations and employs over testing capabilities for all categories of tires. 23,920 people. In addition, Michelin tires are fitted every day on various vehicles and machines and tested repeatedly on tracks, roads, highways and job sites QUALITY around the world.

Before, during and after the manufacturing process, Michelin tires are processed and systems INTEGRITY tested to ensure quality control. New methods of testing are always being developed, to keep pro- Because the tire is the vital contact between the ducing an outstanding product. driver and the road, Michelin is dedicated to providing customers with tires built for outstanding Engineers in physics, chemistry, electronics and performance and dependability at low cost-per- other fields use a wide range of materials and tech- mile. niques. Electron microscopy, x-rays, holography, transmission and absorption spectography, high- At Michelin, there is only one boss — the cus- speed photography, infrared thermograph testing tomer. It is the customer who judges the product and various other investigative techniques are used and ultimately decides whether the company suc- to study the tire and the tire-and-wheel-assembly ceeds or fails. So Michelin puts its considerable interaction with the rest of the vehicle. technological strength into a full line of radial tires to meet customer needs. Quality control goes beyond the laboratory to the production line itself. At each stage of the man-

2 MICHELIN’S MAJOR ACHIEVEMENTS

For over a century now, Michelin has been building a worldwide reputation for technological breakthrough after breakthrough. The historical highlights presented here are some that have made the company what it is Section One

today – and the modern tire what it is today. TIRE SELECTION

1889 Brothers Edouard and Andre Michelin 1957 Michelin develops the radial tire for founded the company as a small rubber earthmovers. factory in Clermont-Ferrand, France. 1968 The Michelin® XWW tire becomes the first 1891 Michelin introduces the first pneumatic original equipment radial to be fitted on (air-filled) tire, which is easier to mount American cars as Michelin radializes the and repair. U.S. market.

1895 The first pneumatic car tire (from Michelin) 1970 Michelin opens its first North American helped make the automobile more manufacturing plant in Canada. practical. 1975 Michelin opens its first manufacturing 1906 Michelin develops the first removable rim plants in the United States. and first spare tire which made repairs simpler. 1979 Michelin introduces the first low-profile truck tire, which improves mileage, fuel 1908 The first dual truck tires increase a vehicle’s economy and handling. carrying capacity, another Michelin innovation. 1981 Michelin patents the first radial for jet airplanes to help provide significant weight 1908- Michelin produces tires in the United savings. 1931 States at a Milltown, NJ plant, which was closed in response to the Great Depression. 1987 The first radial for motorcycles is launched by Michelin. 1923 Michelin invents the first low-pressure passenger car tire to help enhance ride 1991 New fuel savings technology is announced comfort and traction. for passenger and truck tires.

1929 Michelin next turns to the rails, developing 1992 First full line of fuel-efficient “Advanced the first rubber tire for railroad cars, Technology” truck tires introduced for long helping to add comfort and reduce noise. haul service.

1938 Michelin replaces the usual textile fabric of a 1993 Michelin introduced the “Green” tire for ® tire with steel wire, the “Metallic,” which automobiles with its XSE technology. was the forerunner of the steel-belted radial. 1995 Michelin introduces the world’s first 1946 A revolution begins. Michelin patents the 7-year / 700,000 mile / 3 retread casing first steel-belted radial, giving drivers warranty distinct advantages over bias-ply tires: 2000 Michelin introduces the X One® Product longer mileage, better ride comfort, fewer Line. flats, improved traction and greater fuel economy. 2003 Michelin introduces the latest fuel savings products: the XZA3™, XDA3™, and the 1950 Michelin Tire Corporation, incorporated in Energy tire line. New York, begins selling tires in North America.

1951 Michelin introduces the first radial ply truck tire.

3 TIRE SELECTION Section One WHICH MICHELIN® TIRE?

The choice of tire type depends upon the application of the tire and wheel position. No matter what your application may be, Michelin has a tire specifically designed for it. These applications include the following: XZE® XZE®2/XZE®2+ XDE® M/S

TRUCK TIRE APPLICATIONS Long Haul (A) The Long Haul application is composed of busi-

nesses operating primarily in common carrier and XDS® XDE®2+ X One® XDA-HT™ lease rental vocations. Vehicle annual mileage – 80,000 to 200,000.

XTE™ XTE2® WIDE BASE X One® XTE™

XZA3™ XZA2® XZA®-1+

On/Off Road (Y) On/Off Road tires are designed to help provide the durability and performance necessary in highly XZA2® ENERGY XDA3™ XDN®2 aggressive operating conditions at limited speeds. Vocations such as construction, mining and refuse use these highly specialized tires. Vehicle annual mileage – 10,000 miles to 70,000.

XD4® XT-1® X One® XTE™

XZY®3 XZY-2™ XZY®

X One® XDA-HT™ X One® XDA® X One® XTA®

® ™ ™ Regional (E) XZY 3 WIDE BASE XZL WIDE BASE XDY-2 The Regional application is made up of busi- nesses such as public utilities, government – federal, state, and local, food distribution/process, manufacturing/process, petroleum, and schools operating within a 300-mile radius. Vehicle annual XDY®3 XDE® A/T XDY-EX™ mileage – 30,000 miles to 80,000 miles and a 300- mile or less operating radius.

4 Urban (U) SPECIAL TIRE APPLICATION

Urban applications are very short mileage with a • Military high percentage of stop and go. Primarily users are • High Flotation in retail/wholesale delivery and bus fleets. Vehicle • On and Off Road Applications annual mileage – 20,000 miles to 60,000 miles. Section One TIRE SELECTION

XF™ XZL™ X® LISSE COMPACTEUR™ XZU®2 XZU®S X One® XZU®S

COMMERCIAL LIGHT TRUCK TIRE APPLICATIONS XMP™ XML™ XS™ • Highway Tires, All-Wheel-Position • All-Season, All-Terrain Tires • All-Terrain Drive Axle Traction Tires SMALL EARTHMOVER TIRES • Highway Mud & Snow Tires • Mine, coal and quarry type applications (10.00R20, 11.00R20, 12.00R20 and 14.00R24/25)

LTX® A/S LTX® M/S LTX® A/T

XZM™ X MINE® D2 XGLA2™

XPS RIB® XPS TRACTION®

INDUSTRIAL TIRE APPLICATIONS XR™ XK™ XKD1™ (MATERIAL HANDLING)

• Drive & Steer Due to constant innovation and development, • Fork Lift/Utility Vehicles the types and sizes of Michelin® tires are always • Indoor/Outdoor Applications changing. For the most current product offerings, please also refer to the product line brochures, the price lists, the applications data books and the websites: www.michelintruck.com www.michelinearthmover.com

XZM™ X-STRADDLE® X-TERMINAL T™

XZSL™

5 TIRE SELECTION Section One DETERMINING MICHELIN® TIRE SIZE

9. Loaded Radius: The distance from the wheel DEFINITIONS axle centerline to the supporting surface under 1. Tire Size: Michelin® radial truck tire sizes are a tire properly inflated for its load according to designated by the nominal section width in the load and inflation tables. (See Introduction inches or millimeters and the rim diameter for listing of application specific data books.) (e.g. 11R22.5 or 275/80R22.5). The “R” indi- 10. Tire Deflection: Free radius minus the cates a radial tire. Some sizes are also desig- loaded radius. nated with ISO (International Standardization Organization) markings for their load and 11 . Revolutions Per Mile: Revolutions per mile speed rating. (e.g., 144/141K, See Appendix for a tire size and tread is defined as the num- Section). ber of revolutions that the new tire will make in one mile. Data is normally presented for the 2. Aspect Ratio: A nominal number, which rep- loaded tire at its rated load and inflation in the resents the section height, divided by the sec- drive position. Rolling circumference can be tion width and expressed as a percentage. calculated from the revolutions per mile as fol- Example 11R22.5 lows: Aspect Ratio = 90 63,360 = Rolling circumference Example: Tire Size 275/80R22.5 Revs per Mile in inches Aspect Ratio = 80 A tire’s RPM can be determined by measuring, Example 445/50R22.5 (using SAE J1025) or estimated by calculating Aspect Ratio = 50 using a mathematical equation. See Section Nine, Appendix (page 69) for RPM Calculations. 3. Rims: The approved/preferred rims are designated for each size tire. Michelin tires should 4. Overall only be mounted on the rims shown. The rim Width shown first is the preferred rim. Be sure to check rim manufacturers’ specifications. 8. Section 4. Overall Width: The maximum width (cross Height section) of the unloaded tires including pro- truding side ribs and decorations as measured 6. Free on the preferred rim. Overall width will change Radius 0.1 inch (2.5mm) for each 1⁄4 inch change in 3. Rim rim width. Width 5. Overall Diameter 5. Overall Diameter: The diameter of the 7. Nominal C unloaded new tire (measured from opposite Wheel L outer tread surfaces). Minimum dual spacing Diameter should be adjusted accordingly.

6. Free Radius: One-half the overall diameter of 9. Loaded the unloaded new tire. Radius

7. Nominal Wheel Diameter: Diameter of rim seat supporting the tire bead given in nearest whole numbers, e.g. 22.5".

8. Section Height: The distance from rim seat to outer tread surface of unloaded tire. 10. Deflection

6 All the information required to determine the a tire can carry is different if it is mounted in dual proper tire size is contained in the application spe- configuration rather than single. The allowable cific data books. (See Introduction for listing.) A axle loads and the required inflation pressures to sample is shown below. carry these loads are shown in the charts for both

single and dual mountings in the current Michelin Section One

To select the proper tire size for a vehicle, it is Data Book — Truck Tires, Retreads and Commercial TIRE SELECTION necessary to know the maximum axle loads that the Light Truck Tires (MWL40731). The maximum tires will carry and the maximum continuous speed allowable continuous speed is also indicated. at which they will operate. The maximum load that

Specifications for Tread Design: XZA3™

Revs Max. Load Catalog Loaded Overall Overall Approved Min. Dual per Tread Speed Max. Tire Load Max. Tire Load Size Tread Range Number Radius Diameter Width ‡ Rim Spacing ‡ Mile Depth (1) Single Dual kPa

in. mm. in. mm. in. mm. in. mm. 32nds mph lbs. kg. psi lbs. kg. psi

275/80R22.5 XZA3 G 73146 18.6 473 40.1 1018 10.9 277 8.25, 12.3 312 518 19 75 6175 2800 110 5675 2575 110 760 7.50

Note: Rim listed first is the measuring rim. ‡ Overall widths will change 0.1 inch (2.5 mm) for each 1/4 inch change in rim width. Minimum dual spacing should be adjusted accordingly. (1) Exceeding the lawful speed limit is neither recommended nor endorsed. Michelin® tires and tubes are subject to a continuous development program. Michelin North America, Inc. reserves the right to change product specifications at any time without notice or obligations.

Load and Inflation Table for 275/80R22.5 LRG

PSI 70 75 80 85 90 95 100 105 110 kPa 480 520 550 590 620 660 690 720 760 lbs. S 9000 9450 9880 10310 10740 11020 11560 11960 12350 per axle D 16380 17200 18160 18760 19540 20280 21040 21760 22700 kg. S 4080 4280 4480 4680 4880 5000 5240 5420 5600 per axle D 7440 7800 8240 8520 8880 9200 9560 9880 10300

7 TIRE SELECTION Section One LOADS PER AXLE AND RIMS AND WHEELS INFLATION PRESSURES The correct rims and wheels for each tire size are The carrying capacity of each tire size is tabulat- indicated in the specification tables. For complete ed for various inflation pressures by individual tire tire specifications, refer to application specific data load and by axle load for single applications (2 tires) books. (See Introduction for listing.) and dual applications (4 tires). Due to the effects of bouncing and crowned roads, the four tires in dual may not equally share the axle load. Therefore, to MAXIMUM SPEED RESTRICTIONS* protect the tire carrying the largest share of the load, Truck tires should normally be inflated accord- the capacity for duals is not twice the capacity for a ing to the specification tables. The carrying capaci- single formation, but is usually between 5 and 13% ties and inflation pressures specified in these tables less depending on tire size. Insure that the air pres- are determined with the tire’s rated maximum speed sure between the dual tires and/or axles does not in consideration. (See specifications tables for each differ greater than 10 psi. tire’s rated speed.) See current Michelin data book.

All trucks should be weighed, fully loaded, on a Reducing the maximum speed at which the tire scale. Each axle, front and rear, must be weighed sepa- will operate and adjusting inflation pressures rately. Actual gross axle weights should be compared according to the information contained in the fol- with the load and inflation tables to determine the lowing chart can help increase the carrying capacity. inflation pressure required. The load carried by each To use the chart, multiply the load and pressure individual front axle tire should be noted. Motorhomes values taken from the specification section by the should be weighed by wheel end and determined by appropriate load and pressure coefficients given in axle weight by the highest load on the axle. the chart. Note that the coefficients to be applied If the maximum load-carrying capacity of the are dependent on the tire’s rated maximum speed tire is below the actual scale weight, greater carry- and on the speed at which the tire will be used. ing capacity tires should be used. This means Give special attention to rim/wheel or vehicle axle either a tire with a higher load range or ply rating, ratings that may be exceeded by the increased load or a larger tire size. and pressure.

If the maximum load can be carried by the min- The following coefficients may be used by the imum pressure, then a smaller size tire or a lower vehicle manufacturer in determining the maximum ply rated tire should be considered dependent on gross axle weight rating (GAWR), bearing in mind the application and operation of the vehicle. rim or wheel and other component limitations. Never reduce air pressure below minimum data For existing vehicles or for speeds less than 20 mph book specification. Consult Michelin for specific (32 kph) please consult Michelin North America, Inc. situations. These limits apply only to Light Truck and Ambient temperature will affect the air pres- Truck tires, but do not include Special Application sure within the tire. For every 10-degree tires, tires for high cube vans and low bed trailers. temperature change, pressure readings will change between 1 and 2 pounds. Consider this when * Exceeding the legal speed limit is neither recommended nor endorsed. checking pressures.

Additionally, altitude can have a slight effect on air pressure. For every 1,000 feet increase in altitude above sea level, air pressure will increase approximately 1/2 psi. For example, a tire inflated to 100 psi at sea level will read slightly over 102 psi in Denver, Colorado.

Please consult with Michelin for additional information on cold and hot climate corrections.

8 STATIC AND LOW SPEED LOAD AND PRESSURE COEFFICIENTS

Do not exceed loads or air pressure limits of the wheel or rim without permission of the component manufacturer. Section One

TIRE AND RIM ASSOCIATION STANDARD TIRE SELECTION (These Tables apply to tires only. Consult rim/wheel manufacturer for rim/wheel load and inflation capacities.)

Load limits at various speeds for radial ply truck-bus tires used on improved surfaces. (1)

Exceeding the legal speed limit is neither recommended nor endorsed. A. METRIC AND WIDE BASE TIRES B. CONVENTIONAL TIRES The service load and minimum (cold) inflation must comply The service load and minimum (cold) inflation must comply with the following limitations unless a speed restriction is indi- with the following limitations unless a speed restriction is indicated on the tire or the manufacturer rates the tire at 75 mph or cated on the tire or the manufacturer rates the tire at 75 mph or above. (See Table C below.) above. (See Table D below.)

Radial Ply Tires Radial Ply Tires Speed Range* % Load Change Inflation Pressure Speed Range* % Load Change Inflation Pressure (mph) Change (mph) Change 71 thru 75 -12% +5 psi 71 thru 75 -12% +5 psi 66 thru 70 -4% +5 psi 66 thru 70 -4% +5 psi 51 thru 65 None No increase 51 thru 65 None No increase 41 thru 50 +7% No increase 41 thru 50 +9% No increase 31 thru 40 +9% No increase 31 thru 40 +16% No increase 21 thru 30 +12% +10 psi 21 thru 30 +24% +10 psi 11 thru 20 +17% +15 psi 11 thru 20 +32% +15 psi 6 thru 10 +25% +20 psi 6 thru 10 +60% +30 psi 2.6 thru 5 +45% +20 psi 2.6 thru 5 +85% +30 psi Creep thru 2.5 +55% +20 psi Creep thru 2.5 +115% +30 psi Creep (2) +75% +30 psi Creep (2) +140% +40 psi Stationary +105% +30 psi Stationary +185% +40 psi Note: For bias ply tires please consult the TRA Year Book. Load limits at various speeds for radial ply truck-bus tires, rated at 75 mph or above, used on improved surfaces. (1)

C. METRIC AND WIDE BASE TIRES D. CONVENTIONAL TIRES

Radial Ply Tires Radial Ply Tires Speed Range* % Load Pressure Inflation Pressure Speed Range* % Load Pressure Inflation Pressure (mph) Change (mph) Change 71 thru 75 None No increase 71 thru 75 None No increase 66 thru 70 None No increase 66 thru 70 None No increase 51 thru 65 None No increase 51 thru 65 None No increase 41 thru 50 +7% No increase 41 thru 50 +9% No increase 31 thru 40 +9% No increase 31 thru 40 +16% No increase 21 thru 30 +12% +10 psi 21 thru 30 +24% +10 psi 11 thru 20 +17% +15 psi 11 thru 20 +32% +15 psi 6 thru 10 +25% +20 psi 6 thru 10 (3) +60% +30 psi 2.6 thru 5 +45% +20 psi 2.6 thru 5 (3) +85% +30 psi Creep thru 2.5 +55% +20 psi Creep thru 2.5 (3) +115% +30 psi Creep (2) +75% +30 psi Creep (2)(3) +140% +40 psi Stationary +105% +30 psi Stationary (3) +185% +40 psi

(1) This information does not apply to off-road tires. (2) Creep – Motion for not over 200 feet in a 30-minute period. (3) Apply these increases to dual loads and inflation pressures. Note 1: The inflation pressures shown in the referenced tables are minimum cold pressures for the various loads listed. Higher pressures should be used as follows: A. When required by the above speed/load table. B. When higher pressures are desirable to obtain improved operating performance. Note 2: Load limits at various speeds for: Tires used in highway service at restricted speed. Mining and logging tires used in intermittent highway service *Exceeding the legal speed limit is neither recommended nor endorsed. 9 TIRE SELECTION Section One MICHELIN® TRUCK TIRE SIZE EQUIVALENT LOW-PROFILE SIZES MARKINGS MICHELIN T&RA REPLACES Most truck tire sizes are indicated by the section 235/80R22.5 245/75R22.5 9R22.5 width in inches, followed by R for radial, followed by 255/80R22.5 265/75R22.5 10R22.5 the rim or wheel diameter in inches: 275/80R22.5 295/75R22.5 11R22.5 275/80R24.5 285/75R24.5 11R24.5 TUBELESS 11R22.5 11 = nominal section in inches R = radial EQUIVALENT X ONE® TIRE SIZES 22.5 = rim or wheel diameter in inches Dual Size X One® Size 11R22.5, 275/80R24.5 455/55R22.5 275/80R22.5 445/50R22.5

REGROOVING

Only Michelin truck tires that are marked “REGROOVABLE” on the sidewall may be regrooved. After regrooving, you must have at least MICHELIN® LOW-PROFILE TRUCK 3⁄32" of under tread covering the top ply. If steel is TIRES exposed the tire must be scrapped or retreaded. In addition, some tread designs will have a regrooving The Low-Profile tire is marked in accordance depth indicator as shown below. Do not regroove with the ISO (International Standardization below the depth of the indicator. Organization) system and contains load indices, It is the responsibility of the regroover to assure which indicate the load capacity of the tire in single that all Federal Regulations and in dual usage. are met. See U. S. Code of Example: 275/80R24.5 LRG 144/141K 1.6 mm Federal Regulations: Title 275 = nominal cross section in mm (metric) 49, Transportation; Parts 80 = aspect ratio 4.0 mm 569 and 393.75. R=radial 1.6 mm = 2/32nds 24.5 = rim or wheel diameter in inches Depth Indicator 4.0 mm = 5/32nds LRG = load range G 144 = load index in single mounting 141 = load index in dual mounting K=speed code indicating maximum speed of the tire

Michelin introduced the first low-profile radial truck tire for long haul in 1979 to meet the needs of America’s transportation industry. The Michelin® low-profile radial truck tire has established new standards for America’s tires. SIPING

Compared to standard radial tires, the low- There is no reason to ‘sipe’ new Michelin tires profiles offer: (this includes newly retread tires). Drive tires (M/S) • Longer original tread mileage are optimized to provide desirable traction in dry, • Greater casing life wet, snow and icy conditions. “Siping” may be ben- • Lower weight for increased payloads eficial when tires become worn. “Siping” does not • Lower height for greater clearance on trailers automatically affect the warranty. Michelin’s war- and/or greater cargo space with a newly ranty covers defects in workmanship and material. designed trailer If a tire fails or is rendered unserviceable as a result • Excellent traction, handling and stability. of ‘siping’ the tire is not warrantable.

10 TRUCK TYPE BY WEIGHT CLASS

CLASS 1 CLASS 2 CLASS 3 CLASS 4 CLASS 5 Section One TIRE SELECTION 6,000 Ibs. 6,001 to 10,000 Ibs. 10,001 to 14,000 Ibs. 14,001 to 16,000 Ibs. 16,001 to 19,500 Ibs. GVW and less GVW GVW GVW GVW

MILK/BREAD MILK/BREAD MILK/BREAD CONVENTIONAL VANRACK

UTILITY VAN UTILITY VAN COMPACT VAN LARGE WALK-IN LARGE WALK-IN

PICK-UP PICK-UP WALK-IN BUCKET

COMPACT VAN COMPACT VAN TREE SPECIALIST

WALK-IN WALK-IN BOTTLED GAS

MULTI-PURPOSE MULTI-PURPOSE

CREW COMPARTMENT CREW COMPARTMENT PICK-UP PICK-UP

PANEL MINI

11 TIRE SELECTION Section One TRUCK TYPE BY WEIGHT CLASS

CLASS 6 CLASS 7 CLASS 8 TRAILER NOTES 19,501 to 26,000 Ibs. 26,001 to 33,000 Ibs. 33,001 Ibs. and over Weight: Not specified GVW GVW

GVW = Gross Vehicle Weight. The total weight of TOW HOME FUEL FUEL VAN the loaded vehicle includes chassis, body and payload. FURNITURE TRASH DUMP DOUBLES GCW = Gross Combination Weight. STAKE FIRE ENGINE CEMENT LIQUID TANK Total weight of loaded tractor- trailer combination includes tractor- COE VAN SIGHTSEEING REEFER DRY BULK trailer and payloads.

SCHOOL TRANSIT TANDEM AXLE VAN LOGGER GAWR = Gross Axle Weight Rating. Maximum allow- SINGLE AXLE VAN INTERCITY PLATFORM able load weight for a specific spindle, axle, wheel and rim combination. BOTTLER GCW TO 65,000 GCW TO 80,000 DROP FRAME

Identical vehicles may appear in dif- LOW PROFILE COE MEDIUM LOW PROFILE DUMP ferent vehicle CONVENTIONAL TANDEM COE weight classes. This is because of a difference in the components installed HIGH PROFILE COE HEAVY CONVENTIONAL REEFER in each vehicle such as engines, transmissions, rear axles and even tires HEAVY TANDEM DEEP DROP that are not readily CONVENTIONAL discernible in the external appearance of those particular vehicles. COE SLEEPER AUTO TRANSPORTER

12 Section Two MOUNTING THE TIRE

WARNINGS! Tire and rim servicing can be danger- Any inflated tire mounted on a rim ous and must be done only by contains explosive energy. The use trained personnel using proper tools of damaged, mismatched or improp- and procedures. Failure to read and erly assembled tire/rim parts can comply with all procedures may cause the assembly to burst apart result in serious injury or death to with explosive force. If you are you or others. struck by an exploding tire, rim part or the air blast, you can be seriously Re-inflation of any type of tire and injured or killed. rim assembly that has been operated Section Two

in a run-flat or underinflated condi- Re-assembly and inflation of mis- MOUNTING THE TIRE tion (80% or less of recommended matched parts can result in serious operating pressure) can result in seri- injury or death. Just because parts ous injury or death. The tire may be come in together does not mean that damaged on the inside and can they belong together. Check for explode while you are adding air. proper matching of all rim parts The rim parts may be worn, damaged before putting any parts together. or dislodged and can explosively separate. Refer to RMA Tire Information Mismatching tire and rim diameters Service Bulletin on potential “zipper is dangerous. A mismatched tire and ruptures” (TISB 33 number 2). rim assembly may explode and can result in serious injury or death. This Use of starting fluid, ether, gasoline or warning applies to any combination any other flammable material to lubri- of mismatched components, such as cate, seal or seat the beads of a tube- 14" and 14.5", 15" and 15.5", 16" and less tire can cause the tire to explode 16.5", 17" and 17.5", 18", and 18.5" or can cause the explosive separation or 19" and 19.5" tires, and rim combi- of the tire/rim assembly resulting in nations. Never assemble a tire and serious injury or death. The use of rim unless you have positively identi- any flammable material during tire fied and correctly matched the parts. servicing is absolutely prohibited.

GENERAL INSTRUCTIONS FOR TUBELESS TIRE MOUNTING/DEMOUNTING

A tire cannot perform properly unless it is mount- For detailed instructions on mounting and demounted on the correct size rim or wheel. The following are ing truck tires on particular types of rims and wheels, general instructions for demounting and mounting refer to the instructions of the rim and wheel manu- Michelin® tubeless tires, including the X One®. facturer or the RMA wall charts.

13 Directional Tires. When mounting any direc- • Assists proper bead seating (tire/rim centering) tional tire, insure directional arrow points toward and helps to prevent eccentric mountings. the direction of travel during the original life. Avoid using excessive amounts of lubricants.

1. SELECTION OF PROPER COMPONENTS CAUTION: It is important that tire lubricant AND MATERIALS: be clean and free of dirt, sand, metal shavings or a. All tires must be mounted on the proper other hard particles. The following practice is rec- rim/wheel as indicated in the specifications ommended: tables. For complete tire specifications, refer to a. Use a fresh supply of tire lubricant each day application specific data books. (See

MOUNTING THE TIRE drawing from a clean supply and placing the Introduction for listing.) lubricant in a clean portable container. Section Two b. Make certain that rim/wheel components are b. Provide a cover for the portable container and/or properly matched and of the correct dimen- other means to prevent contamination of the sions for the tire. lubricant when not in use. For lubricants in solution, we suggest the following method c. Always install new valve cores, and metal valve which has proven to be successful in helping to caps containing plastic or rubber seals. minimize contamination and prevent excess d. Always replace any rubber valve stem on a 16" lubricant from entering the tire casing: provide a through 19.5" wheel. special cover for the portable container that has a funnel-like device attached. The small opening e. Always use a safety device such as an inflation of the funnel should be sized so that when a cage or other restraining device that will con- swab is inserted through the opening into the strain all rim/wheel components during an reserve of lubricant and then withdrawn, the explosive separation of a multi-piece rim/wheel, swab is compressed, removing excess lubricant. or during the sudden release of the contained air This allows the cover to be left in place provid- of a single piece wheel that is in compliance ing added protection. A mesh false bottom in with OSHA standards. Never stand over a tire or the container is a further protection against con- in front of a tire when inflating. Always use a taminants. The tire should be mounted and clip-on valve chuck with an in-line valve with a inflated promptly before lubricant dries. pressure gauge or a presettable regulator and a sufficient length of hose between the clip-on 3. PREPARATION OF WHEELS, RIMS chuck and in-line valve (if one is used) to allow AND TIRES: the employee to stand outside the trajectory path when inflating. Note: Safety cages, Never weld or apply heat to a rim or wheel on portable and/or permanent are also available for which a tire is mounted. inflation of the X One® tire assemblies. a. Always wear safety goggles or face shields when buffing or grinding rims or wheels. 2. TIRE AND RIM LUBRICATION: b. Inspect wheel/rim assemblies for cracks, distor- It is essential that an approved tire mounting tion, and deformation of flanges. Using a file lubricant be used. Preferred materials for use as and/or emery cloth, smooth all burrs, welds, bead lubricants are vegetable oil soaps or animal dents, etc. that are present on the tire side of the soaps, in solution. Never use antifreeze, silicones, rim. Inspect the condition of bolt holes on the or petroleum-base lubricants. Improper ratios of wheels. approved lubricants and water may have a harmful effect on the tire and wheel. c. Remove rust with a wire brush and apply a rust inhibiting paint on steel wheels. The lubricant serves the following three purposes: • Helps minimize the possibility of damage to the d. Remove any accumulation of rubber or grease, tire beads from the mounting tools. which might be stuck to the tire, being careful not • Helps ease the insertion of the tire onto the rim to damage it. Wipe the beads down with a dry rag. by lubricating all contacting surfaces.

14 MOUNTING THE TIRE

3. RIM WIDTH: FITTING TIRES — NOT ORIGINAL An increase in the tire section may require a EQUIPMENT SIZES wider rim with a greater offset. When fitting tires of sizes different than those 4. OFFSET for dual wheels: specified by the vehicle manufacturer, the follow- The minimum offset required is determined by ing points must be considered: the distance that must be left between the dual tires. 1. GEAR RATIO: A change in tire dimension will result in a change OFFSET for front wheels: in engine RPM at a set cruise speed, which will Wider rims may require a different offset to result in a change in speed and fuel economy. avoid interference with vehicle parts. The effect of tire size change on gear ratio should be considered in individual operations: 5. TIRE CLEARANCES: Section Two • A decrease in tire radius will increase start- All clearances around a tire should be checked: MOUNTING THE TIRE ability tractive torque and decrease geared • To the nearest fixed part of the vehicle, i.e., to and indicated top speed. parts which are not affected by spring deflec- • An increase in tire radius will reduce tractive tion or steering mechanism. torque and increase top geared speed. • To the nearest part of the vehicle, which can be • RPM/SPEED/SIZE: These factors can effect moved, i.e., parts that are affected by spring RPM if corresponding changes are not made to deflection or steering mechanism. engine ratios. Example: 11R24.5 XDA-HT (471 Minimum clearances permissible: rpm) versus 455/55R22.5 XDA-HT (494 rpm). • To a fixed part 15 mm (5/8") 471/494= .953, .953 X 60 mph = 57.21 mph • To a moveable part 25 mm (1") 2. WHEEL DIAMETER: If a smaller wheel diameter is chosen, make a. Lateral Clearances sure that brake clearances are checked before Lateral clearance is the smallest distance lateral- making a recommendation. ly between the tire and the nearest fixed point of the vehicle. An increase in the offset of the inner wheel plus half any increase in the tire section Center Line Center Line will reduce lateral clearance. D D = Minimum Dual Spacing

Lateral Clearance

Overall Width

Offset (Inner) Road Spring

Offset (Outer) Note: The X One® tire should be mounted so that the tire sits outward similar to an outer dual tire. This will offer exceptional lateral clearance. However, use of offset wheels may change Gross Axle Weight Rating (GAWR), con- OUTSIDE INSIDE sult vehicle manufacturer.

15 Vertical Clearance (VC)

Lateral Clearance X One

Axle Stop (Must be smaller than VC or tire tread will touch before axle stop closes up) Road Spring MOUNTING THE TIRE CORRECT PLACEMENT

Section Two Vertical Clearance (VC)

Body Clearance X One

c. Longitudinal Clearances Road Spring The semi-elliptic spring method of suspension permits the axle to move back longitudinally as INCORRECT PLACEMENT well as vertically when the spring deflects. As a guide, the maximum backward movement may b. Vertical Clearances be taken as one third of the distance between the shackle pin centers. The remaining longi- A certain vertical clearance exists between the tudinal clearance must be noted. top of the tread and some part of the vehicle immediately above it, usually a fender. This will vary as the springs operate. The vertical move- ments of the whole axle, in relation to the whole chassis, are normally limited by an axle stop. 75 mm. (3") When measuring vertical clearance, also measure the axle stop clearance; the difference is the remaining vertical clearance. When checking vertical clearance, consideration must be given to the degree of tread wear and an allowance of 1" must be made if the tread on the existing tire is between 2⁄ 32" to 4⁄32". Fixed Pivot Swing Pivot Vertical and body clearances are decreased by Fixed Pivot any increase in the free radius of the tire. Spring Shackle Check to be sure that the body clearance is not less than the vertical clearance. A fender bolt may be closer to the tire than the fender. This then is the smallest distance and should be recorded. (This may be corrected by reversing Longitudinal Clearance the bolt.)

16 d. Front Wheel Clearances increase in the cross section of each outside tire and the increase in offset of each outside wheel. The clearances of both front wheels must be measured on both steering lock positions.

Clearances of front wheels must be checked turning wheels from full left lock to full right Overall Width of Body lock, since the minimum clearance might occur at some intermediate point. Measure Here

Check Clearances Here and All Positions From Lock to Lock Not Here

Overall Width

7. SPARE WHEEL RACK:

Always check the spare wheel rack to see that Section Two

the tire will fit. MOUNTING THE TIRE 8. LEGAL LIMITS:

Bottom View Most states and provinces in North America have legal limits for vehicle carrying capacities, 6. OVERALL WIDTH: overall vehicle dimensions, and minimum ground clearances. Each of these factors must When fitting larger tires, the overall width of the be taken into consideration. Check with local vehicle across the tires is increased by half of the jurisdictions.

TUBELESS TIRE MOUNTING/DEMOUNTING

Re-inflation of any type of tire/rim not use hammers of any type. Striking a assembly that has been operated in a wheel/rim assembly with a hammer of any type run-flat or underinflated condition can damage the tire or wheel and endanger the (80% or less of recommended pres- installer. Use a steel duck billed hammer only as a sure) can result in serious injury or wedge. Do not strike the head of a hammer with death. The tire may be damaged on another hard faced hammer – use a rim mallet. the inside and can explode while you 3. Apply the lubricant to all surfaces of the bead are adding air. The rim parts may be area of the tire. worn, damaged or dislodged and can explosively separate. 4. Beginning at the valve, remove the tire using tire irons designed for this purpose. Starting at the valve will minimize chances of damaging the bead. Make certain that the flange with the DEMOUNTING OF TUBELESS TIRES tapered ledge that has the shortest span to the 1. Before loosening any nuts, deflate the tire by re- drop center is facing up. Always attempt to moving the valve core. keep the bead not being worked by the irons, in the full depth of the drop center cavity. 2. With the tire assembly lying flat, break the bead seat of both beads with a bead breaking tool. Do

17 1. Lay tire/wheel assembly horizontally and inflate MOUNTING TUBELESS TIRES to no more than 5 psi to position the beads on 1. Inspect the condition of the bolt holes on the the flanges. wheels, look for signs of fatigue. Check flanges 2. To complete the seating of the beads, place the for excessive wear by using the wheel manufac- assembly in an approved safety cage and inflate tures flange wear indicator. to 20 psi. Check the assembly carefully for any 2. Replace valve core and inspect valve stem for signs of distortion or irregularities from run-flat. damage and wear. We recommend always If run-flat is detected, scrap the tire. replacing the valve stem and using a new valve stem grommet. Insure valve stem is installed 3. If no damage is detected, continue to inflate to the MOUNTING THE TIRE using the proper torque value. 80-125 in/lbs maximum air pressure marked on the sidewall. RMA recommends that if the tire suspected of

Section Two (7-11 ft/lbs) for standard aluminum wheels and 35-55 in/lbs (3-5 ft/lbs) for standard tubeless being run underinflated be overinflated by 20 psi steel wheels. and be remain in the cage for 20 minutes prior to handling. 3. When applying lubricant to the rim, lubricate the entire rim surface from flange to flange. 4. Insure that the guide rib (GG Ring) is positioned The tire should be mounted and inflated before concentric in relation to the rim flange with no the lubricant dries. greater than 2/32" of difference found circumferentially. If bead(s) did not seat, deflate tire, 4. With the rim short side (narrow side) up, lay the relubricate the bead seats and re-inflate. tire over the rim at the valve side and work it on with proper tubeless tire tools, making full use of the drop center well. The 19.5-inch should be mounted from the short side. Care should be taken to insure that any internal monitoring system is not damaged or dislodged during this GG-Ring service.

5. Do not use any kind of hammer. Bead damage may occur leading to tire destruction. Wheel

6. The X One® tire is designed to replace dual tires on the drive and trailer positions of tandem over the road vehicles and the tires must be mounted on 22.5 x 14.00" size wheels. Position the tire and wheel assembly so the valve stem is facing outward, away from the vehicle.

INFLATION OF TUBELESS 5. After beads are properly seated, inflate to 100 TIRES psi, then adjust tire pressure to recommended operating pressure. Check valve core for leak- Re-inflation of any type of tire/rim age, then install suitable valve cap. assembly that has been operated in a Never inflate or re-inflate any tires that have run-flat or underinflated condition been run underinflated or flat without careful (80% or less of recommended pres- inspection for damage, inside and out. sure) can result in serious injury or death. The tire may be damaged on the inside and can explode while you are adding air. The rim parts may be worn, damaged or dislodged and can explosively separate.

18 MOUNTING THE ASSEMBLY ON THE VEHICLE

When wheel assemblies are mounted on a vehicle, be sure that the valves do not touch the brake MEASURING TIRES IN DUAL drums or any mechanical part of the vehicle. When ASSEMBLY mounting the X One® tire onto a vehicle, position Measuring the circumferences of the tires with the tire so that the tire sits on the outbound side of an endless tape after they are on the rims and the wheel similar to where the outer dual would inflated, but before they are applied to a vehicle, is normally be positioned. Also position the tire and the most accurate method. The endless tape, as the wheel assembly so the valve stem is facing outward, name signifies, is a tape made of one half inch away from the vehicle. bending steel, one end of which passes through a Valves of dual tires should be diametrically slot at the other end of the tape and forms a loop. opposite. Ensure that the inside valve is accessible Measuring in this manner takes into account any in order that the air pressure can be checked and irregularities in wear. the tire inflated when necessary.

Measuring with Endless Tape Section Two Tires mounted in duals must be matched so that the maximum difference between the diame- MOUNTING THE TIRE ters of the tires does not exceed 1⁄4" (equates to 4⁄32nds of tread depth) or a circumferential difference of 3⁄4". Failure to properly match dual tires will result in the tire with the larger diameter carry- In checking tires already on a vehicle, either (A) ing a disproportionate share of the load. a square (similar to but larger than a carpenter’s Mismatched duals can lead to rapid wear and square), (B) a string gauge, (C) a large pair of excessive fatigue. calipers, or (D) a wooden straight edge long enough to lie across the treads of A) Use of a Square IMPORTANT: Check to insure that you know all four tires, may be which mounting system you are working with and used. that the components are correct. See Appendix, Section 9, Hub and Stud Piloted Wheel Types. (Reprinted with permission from RP 222A, User’s Guide to Wheels and Rims, published by the Technology & Maintenance Council (TMC) of the American Trucking Associations, 2200 Mill Road, Alexandria, VA 22314 (703) 838-1776 .)

B) Use of String Gauge DUAL SPACING

It is also important that sufficient space is provided between dual tires to allow air to flow and cool the tires and to prevent the tires from rubbing against one another.

To make sure dual spacing is correct, simply measure the two tires from center to center of the tread, and refer to the minimum dual spacing column in the application data books.

19 C) Use of the D) Use of a Wooden Straight Edge TIRE MIXING Calipers IMPROPER TIRE MIXING CAN BE DANGEROUS

Four Wheel Trucks: For the best performance it is recommended that the same size, design and construction of tire be used on all four wheel positions. If only two Michelin® radials are mounted with two non-radials, the radials should be mounted on the rear. If tires of different design are mixed on a vehicle in any configuration, they MOUNTING THE TIRE should not be used for long periods and speeds*

Section Two should be kept to a minimum. MATCHING TIRES ON TANDEM Mixing or matching of tires on 4-wheel drive AXLES vehicles may require special precautions. Always check vehicle manufacturers’ Owners Manual for Tandem drive rear axles without an inter-axle their recommendations. differential necessitate that the eight tires are matched so that the average tire circumference on Trucks with more than four wheel the one axle is within 3⁄4" of the average tire cir- positions: For best performance, it is recom- cumference on the other axle. mended that radial and non-radial tires should not be mixed in dual fitment. It is unlawful and danger- Since any one tire of the size used with these ous to mix radials and bias tires on the same axle. axles may lose as much as 2 1⁄2" in circumference due to normal wear and still be serviceable, it is readily seen that a wide difference in tire circumference may exist. RUNOUT

The best method of avoiding damage due to When installing new tire/wheel assembly on the having tires of unequal circumferences is to steer axle, this is an ideal time to first verify the inspect and match tires so that the average tire concentricity of the guide rib area as well as insur- diameter on one axle is within 1 ⁄ 4" (equates to ing that both the radial and lateral runout measure- 4/32nds of tread depth) of the average tire diame- ments are the lowest possible to offer the driver the ter on the other axle. Equal tire inflation at the smoothest ride. The variation in at least four mea- pressures recommended by the tire manufacturer surements around the wheel should be no greater should be maintained. than 2⁄32nds of an inch. See Section Nine, Appendix, ‘Runout and Vibration Diagnosis’ for procedures.

*Exceeding the legal speed limit is neither recommended or endorsed.

20 Section Three EXTENDING THE TIRE LIFE

Once the tires have been put into operation, it is important that they and the vehicle are properly maintained in order to obtain the maximized performance for which the tires have been designed.

MAINTAINING THE TIRE

INFLATION PRESSURE Use an accurate calibrated tire gauge to check pressures. (Do not use “Tire Billys” to hit tires as an The most critical factor in tire maintenance is inflation check. This is an unreliable method.) proper inflation. No tire or tube is completely For optimized tire performance, it is usually impervious to loss of air pressure. To avoid the best to use the tire inflation pressure shown in the hazards of underinflation, lost air must be application data books for the particular axle load. replaced. Exceeding this pressure could result in reduced Driving on any tire that does not have the cor- traction and tread life. rect inflation pressure is dangerous and will cause However, for steering axle tires, it is often tire damage. acceptable to use inflation pressures greater than Any underinflated tire builds up excessive heat that shown in the application data books for the that may result in sudden tire destruction. The particular axle load. However, when operating the correct inflation pressures for your tires are a func- tire at maximum rated load never exceed the maxi- tion of many factors including: load, speed, road mum sidewall specified pressure by more than 10% surface and handling. unless technical approval is obtained from

® Michelin North America, Inc. Never inflate to cold

Consult a Michelin Truck Tire dealer or Section Three pressure beyond the rated capacity of the rim. Michelin data books for the proper inflation pres- EXTENDING TIRE LIFE sures for your application. See the Introduction Following are two examples of applying the pre- for complete listings of the Michelin data books. vious considerations to an operation where the user mounts new 275/80R22.5 XZA-1+ tires on a Check inflation pressures on all your tires at steer axle and desires to increase the air pressure in least once a week, including spares, before driving order to see if this will help alleviate the occurrence when tires are cold, especially when vehicle is used of irregular wear. by more than one driver. Example 1: If the axle load is 10,310 lbs., then Failure to maintain correct inflation pressure the table in the data book specifies a corresponding may result in sudden tire destruction, improper pressure of 85 psi. So, the user can increase the vehicle handling - possibly resulting in an accident pressure 15-20 psi above that to 100 or 105 psi. - and may cause rapid and irregular tire wear. Therefore, inflation pressures should be checked Example 2: If the axle load is 12,350 lbs., then weekly and always before long distance trips. the table in the data book recommends 110 psi. As this is the maximum load of the tire, only a 10% Pressures should be checked when tires are pressure increase is permitted. Thus the adjusted cold; in other words, before they have been driven. pressure would be limited to 120 psi. The ideal time to check tire pressures is early morn- ing. Driving, even for a short distance, causes tires This procedure should not be applied “across to heat up and air pressures to increase. the board.” If you are getting satisfactory tire performance and wear with “table” pressures for a Never bleed air from hot tires, as your tires will given load, then leave well enough alone. then be underinflated. Make sure to check both tires in a dual fitment. Pressures should be the same. Overinflation can increase road shocks and Maximum allowable difference between tires in dual vibrations transmitted to the vehicle. or between axles should be no greater than 10 psi. 21 NOTE: In no case should the maximum capacity of the wheel/rim be surpassed. Consult wheel/rim CENTRAL TIRE INFLATION manufacturer’s specifications. SYSTEM OR PRESSURE

NOTE: The following illustration is based on the MONITORING SYSTEMS recommended inflation pressure from the data Most of the systems on the market are capable book for the load being carried. of maintaining a cold inflation pressure in the tires of 90 to 95 psi. Insure your system will maintain a high enough operating pressure in order for the EFFECTS OF INFLATION PRESSURE ON TIRE LIFE tires to support the load at the desired speed. Tires 100 on vehicles with these systems should still be visu- 90 ally inspected before and after use. 80 Loss of Service Due 70 to Overinflation 60 MILEAGE RECREATIONAL VEHICLES OR TIRE 50 LIFE Loss of Service Due IN % 40 to Underinflation Michelin recommends weighing each wheel 30 position of the vehicle to determine the correct 20 cold inflation pressure per tire for each wheel end. 10 Refer to the Michelin Recreational Vehicle Tire 0 Guide (MDL40660) for specific recommendations 60 80 100 120 in inflation pressures and detailed proper proce- % OF RECOMMENDED INFLATION PRESSURE dures for weighing RVs. See Section Nine, of this EXTENDING TIRE LIFE publication, Appendix for ‘Runout and Vibration

Section Three Diagnosis’.

TIRE INSPECTION

UNDER- OVER- PROPER While checking inflation pressures, it is a good INFLATION INFLATION INFLATION time to inspect your tires. Anytime you see any damage to your tires or wheels/rims, see any Michelin Truck Tire dealer at once. Tread Contact Tread Contact Tread Contact With Road With Road With Road Before driving, inspect your tires, including the spare, and check your air pressures. If your pres- UNDERINFLATION sure check indicates that one of your tires has lost Causes abnormal tire pressure of 4 psi or more, look for signs of penetra- deflection, which builds up heat and causes tions, valve leakage, or wheel/rim damage that may irregular wear. account for air loss. OVERINFLATION Causes tires to run hard and If the tire is 20% below the maintenance air be more vulnerable to impacts. pressure, it must be considered flat. Remove and It also causes irregular wear. inspect for punctures or other damage. If run-flat PROPER INFLATION damage is detected, scrap the tire. Refer to TMC The correct profile for full contact RP 216 Radial Tire Conditions Analysis Guide. with the road promotes traction, braking capability and safety. Always examine your tires for bulges, cracks, Due to the unique casing design of the Michelin® X One®, cuts or penetrations. If any such damage is traditional air pressure adjustment practices for dual tires may not apply to the X One product line. See Section 4 of found, the tire must be inspected by any Michelin this manual and applicable Technical Bulletins. Truck Tire dealer at once. Use of a damaged tire could result in tire destruction, property damage and/or personal injury.

22 DRIVE CAREFULLY DO NOT OVERLOAD

All tires will wear out faster when subjected to The maximum load that can be put on a truck high speeds as well as hard cornering, rapid starts, tire is dependent upon the speed at which the tire sudden stops and frequent driving on surfaces that will be used. Consult a Michelin Truck Tire dealer are in poor condition. Surfaces with holes and rocks or the application data books for complete infor- or other objects can damage tires and cause vehicle mation on the allowable loads for your tires in your misalignment. When you drive on such surfaces, application. Tires that are loaded beyond their drive on them carefully and slowly, and before dri- maximum allowable loads for the particular appli- ving at normal or highway speeds, examine your cation will build up excessive heat that may result tires for any damage, such as cuts or penetrations. in sudden tire destruction, property damage and personal injury.

Some states have enacted "Load Per Inch TREAD DEPTH MEASUREMENTS Width" regulations for the purpose of governing axle weight on (primarily) the steering axle of com- Tires should be measured for wear. This mea- mercial vehicles. These regulations provide a car- surement can be taken in several spots across the rying capacity of a certain number of pounds per tread and around the circumference. However, to each cross-sectional inch across the tire's width. calculate the remaining amount of rubber (know- The determination of the tire's width can vary from ing the new tire tread depth) for a given number of state to state, but presumably would be based upon miles run, the measurement should always be either the tire manufacturer's published technical taken at the same spot on the tread and close to the data for overall width, or the width as marked on center groove of the tire, as shown below: the sidewall of the tire (which may require conversion from Metric to English units). It is recommended to contact your state’s DOT office to confirm the current Load Per Inch Width Law.

For example, if a state allows for 550 pounds per

inch width, a tire marked 11R22.5 could carry up to Section Three 6,050 pounds (11 X 550) or a total of 12,100 pounds on the steer axle (2 X 6,050). Another way to look at EXTENDING TIRE LIFE it is to take the total weight carried, and divide by the stated Inch Width Law to determine the appropriate size tire. If a commercial front end loader (sanitation vehicle) wants to carry 20,000 pounds in a state with a 600 pound per inch width limit (20,000 / 600 = 33.3), you would need a tire that is at least 16.7 inches wide (33.3 / 2). In this case a 425/65R22.5 could legally carry the load (425 / 25.4 = 16.7 inches Metric to English conversion).

The two formulas are: WEAR BARS – Load Per Inch Width Law x tire section width x number of tires = gross axle weight limit. Michelin® truck tires contain "wear-bars" in the – Gross axle weight / Inch Width Law / number grooves of the tire tread, which show up when only of tires = minimum tire section width needed. 2⁄32nds of an inch or less of tread, is remaining. These are referenced on the shoulder by the Do not exceed the gross axle weight ratings Michelin Man™. Tread depths should not be taken (GAWR) for any axle on your vehicle. on the wear bar indicators. At this stage your tires must be removed. Tires worn beyond this stage are dangerous. (Federal law requires truck tires on front axles to have at least 4⁄32nds of an inch tread depth.)

23 If contact is made, it has a greater chance of causing DRIVE AT PROPER SPEEDS tire damage, than at a lower speed. Moreover, driving at high speed decreases the time available to The maximum continuous speed at which avoid accidents and bring your vehicle to a safe stop. Michelin truck tires can be operated is indicated in the Michelin data books. See the Introduction for Do not exceed the maximum pressure capacity complete listings of the Michelin data books. This of the wheel. Consult the wheel manufacturer in speed varies for each type of tire and depends on these cases. the type of application. Consult a Michelin Truck Tire dealer (1-800-TIRE HELP) for assistance in determining the maximum speed for your application. Exceeding this maximum speed will cause the BALANCE AND RUNOUT tire to build up excessive heat that can result in It is customary to check tire balance if the driver sudden tire destruction, property damage and per- makes a ride complaint. Before removing the tire- sonal injury. In any case, you should not exceed wheel assembly from the vehicle, check for radial and reasonable speeds indicated by the legal limits and lateral runout. Bent wheels and rims or improper driving conditions. mounting or flat spotting can cause excessive runout. High speed driving can be dangerous and may If balance is still required, a simple static balance be damaging to your tires. with bubble balancer or a wall mounted axle bearing and hub type gravity balancer should be sufficient. When driving at highway speeds, correct inflation pressure is especially important. However, at Current Technology Maintenance Council lim- these speeds, even with correct inflation pressures, a its from RP 214B Tire/Wheel End Balance and

EXTENDING TIRE LIFE road hazard, for example, is more difficult to avoid. Runout are listed below Section Three

TIRE / WHEEL ASSEMBLY BALANCE AND RUNOUT LIMITS

Tire Position 19.5 Over The Road On-Off Road Wide Base Tires/Wheels Applications Applications Tires/Wheel

Maximum total weight correction expressed in ounces Steer 14 oz. 16 oz. 18 oz. 24 oz. of weight required to correct at rim diameter per rotating assembly Drive/Trailer 18 oz. 20 oz. 22 oz. 28 oz.

Steer/Drive 0.095" 0.095" 0.110" 0.125" Lateral runout for rotating assembly Trailer 0.125" 0.125" 0.125" 0.125" Steer/Drive 0.095" 0.095" 0.110" 0.125" Radial runout for rotating assembly Trailer 0.125" 0.125" 0.125" 0.125"

NOTE: If tire and wheel assembly is within these limits and ride problem still exists, refer to TMC RP648 Diagnosing Ride Complaints.

RECOMMENDED BALANCE AND RUNOUT VALUES FOR DISC WHEELS AND DEMOUNTABLE RIMS

Balance Radial Runout Lateral Runout (See Note 2) (See Note 3) (See Note 3) Tubeless Steel Disc Wheels 6 oz. max 0.07 inch max 0.07 inch max. Tubeless Aluminum Disc Wheels 4 oz. max 0.03 inch max 0.03 inch max Tubeless Demountable Rims N/A 0.07 inch max 0.07 inch max Wide Base Wheels: Steel See Note 1 0.75 inch max 0.75 inch max Aluminum See Note 1 0.30 inch max 0.30 inch max

NOTE 1: Refer to the manufacturer’s specifications for balance and runout values. NOTE 2: Amount of weight applied to rim to balance individual wheel component. NOTE 3: For steel wheels and demountable rims, the area adjacent to the rim butt weld is not considered in runout measurements.

24 STORAGE RECOMMENDATIONS FOR THE USE OF DYNAMOMETERS All tires should be stored in a cool dry place indoors so that there is no danger of water collect- ing inside them. Serious problems can occur with tube-type tires when they are mounted with water trapped between the tire and tube. Due to pressur- ization, the liquid can pass through the inner liner and into the casing plies. This can result in sudden tire failure. Most of the problems of this nature have been due to improper storage, which allowed water to enter the casing. This is a particular problem with tube-type tires because of the difficulty in detecting the water, which collected between the tire and tube. When tires are stored, they should be stored in a cool place away from sources of heat and ozone, such as hot pipes and electric motors. Be sure that surfaces on which tires are stored are SEVERE DAMAGE can result in the crown area clean and free from grease, gasoline or other sub- of radial truck tires when run on dynamometers for stances, which could deteriorate the rubber. Tires extended periods. Quite often the damage is inter- exposed to or driven on these substances could be nal and not discovered until after the vehicle has subject to sudden failure. been put back in service.

In order to avoid the possibility of damaging Michelin® radial truck tires, adhere to the following CHAINS time/speed restrictions and related test parameters: This applies to tire sizes with bead seat diameters of In order to satisfy legal requirements in many 19.5, 20, 22, 22.5, 24 and 24.5 inches. states, you may need to require the use of chains on truck tires. When the use of chains is required, the NOTE: The times for the indicated speed in the Section Three following recommendations should be followed: chart are not additive. EXTENDING TIRE LIFE

1. Chains should only be utilized when necessary. MAXIMUM TIME (MINUTES)

The possibility of damage to the tire or the chain 5 On 8 ⁄8" On 18-20" increases as driving speed and length of travel on Speed (mph)* Dia. Rollers Dia. Rollers the chains increases, and is especially increased by use on dry pavement. As a general rule, 62 (Max.) 2.5 4 chains should be utilized only as long as required, 50 3.5 6 and vehicle speeds should be kept relatively low. 40 5 8.5 2. Since manufacturers have size recommenda- 30 7.5 14 tions for radial ply tires, no matter what type of 20 16 35 “chain” they manufacture, these size recommendations must be adhered to for optimized 10 42 105

utility and performance. *Exceeding the legal speed limit is neither recommended or endorsed.

3. Always be sure to check for proper clearances between chain and vehicle. • Allow a two-hour cool-down between tests. 4. Also follow closely the mounting instructions and procedures of the chain manufacturer. • These limits are for an empty vehicle with tire pressures as indicated on the tire sidewall for 5. Specific chains are available for the X One® X maximum load. product line. Consult Michelin for proper type/size.

25 •Allow a one-hour cool-down after each test before loading vehicle. SPINNING Major tire damage can occur in a short period The maximum allowable center-to-center dis- of time when a tire spins on a surface at high tance between the two rollers in contact with a tire speeds. When the speed difference between the is a function of the sum of tire and roller diameter. wheel with good traction and the wheel without This relationship is shown below: becomes too great, the tire begins to disintegrate. Maximum Roller Spacing = This can occur on any slick surface (such as ice, Tire Diameter + Roller Diameter x 1.15 mud and snow) or on a dry surface where there is a 2 variance in traction. The resulting difference in speed of the assembly can be as high as 4 times the For example: registered speed indicated, resulting in tire, and/or differential damage on the vehicle. MAX. ROLLER SPACING

5 Tire Size 8 ⁄8" Dia. 18" Dia. 275/80R22.5 28" 33.4" ROTATION 255/70R22.5 26" 31.4" Michelin® radial tires should be rotated when necessary. If the tires are wearing evenly, there is no need to rotate. If irregular wear becomes appar- Note that in the above speed/time table a sig- ent or if the wear rate on the tires is perceptively nificant increase in time is allowed on the 18-20 different (from axle to axle for drive tires and side to side for steer tires), then the tires should be rotated

EXTENDING TIRE LIFE inch versus the 8 5⁄8-inch diameter roller. For example, at 30 mph time almost doubles from 7.5 in such a manner as to alleviate the condition. Section Three minutes to 14 minutes. Rotation procedures such as those recommend- If these times and/or speeds are ed by vehicle manufacturers (see TMC RP 642 Total exceeded, irreversible internal dam- Vehicle Alignment) may be followed. age in the tire could result, leading NOTE: There is no restriction on criss-cross rotation. ultimately to tire destruction. NOTE: Directional Tires. When mounting any direc- When it is anticipated that a test will exceed tional tire, insure directional arrow points toward the these time/speed values, use “surrogate” tires (a direction of travel during the original tread life. tire used in place of the normal tire).

26 MAINTAINING THE VEHICLE

Many tire problems can be traced to mechanical conditions in the vehicle. Therefore, to obtain TOE maximized tire performance, vehicles must be Toe is typically the most critical alignment con- properly maintained. dition affecting steer axle tire wear. The purpose of setting toe at a given specification is to allow the tire to run straight during normal operating condi- MAJOR VEHICLE FACTORS WHICH tions. Too much toe-in results in scrubbing from AFFECT TIRE LIFE: the outside inward on both tires and too much toe- out results in scrubbing from the inside outward on both tires. ALIGNMENT Total toe is the angle formed by two horizontal Alignment refers not only to the various angles lines through the planes of two wheels. Toe-in is of the steer axle geometry, but also to the tracking when the horizontal lines intersect in front of the of all axles on a vehicle, including the trailer. The wheels, or the wheels are closer together in front dual purpose of proper alignment is to minimize than in back. Toe-out is when the horizontal lines tire wear and to maximize predictable vehicle han- intersect behind the wheels, or the wheels are closer dling and driver control. One of the challenges of together in back than in front. Toe-in is commonly meeting this goal is that alignments are typically designated as positive, and toe-out as negative. performed on a static, unloaded vehicle sitting on a level floor. The vehicle then operates over varying Steer axle toe is adjustable to reduce wear to the contoured surfaces, under loaded conditions, with leading edge of the tire and also to avoid road wan- dynamic forces acting upon it. Predicting the der. Toe is adjusted in a static, unloaded condition amount of change between static/unloaded/level - so that the tires will run in a straight line under a versus – dynamic/loaded/contoured is difficult dynamic, loaded condition. because many variables affect the amount of The toe measurement will probably change from change. Variables such as Steering System Section Three unloaded to loaded conditions. The amount of

Compliance (i.e., “play”) must be considered in EXTENDING TIRE LIFE change will vary with axle manufacturer, axle rating, making alignment setting recommendations. and steering arm geometry; but it is still fairly pre- We therefore recommend referring to TMC RP dictable. Front axles on most popular Class 8 long 642 Total Vehicle Alignment, which has established haul tractors will change in the direction of toe-out industry recommended target values for the align- about 1⁄32" (0.8 mm or .05 degree) for each 1000 ment of vehicles. pounds of load increase on the steer axle. Cabover tractors with set-back-front-axles typically experience less steer axle change in load from bobtail to loaded than do other configurations. Wheelbase and STEER AXLE GEOMETRY fifth wheel location are also major factors affecting how much load change the steer axle will experience. Since very few Inclined Kingpin Toe-in vehicles continue to use Center Point Steering, the following recommendations are based on the more common Inclined Kingpin Steer Axle Geometry.

27 See Conversion Table at Section Nine, The purpose of caster is to provide self-aligning Appendix for conversion of fractions to millimeters forces on the steer tires to stabilize the vehicle to inches and degrees. See Section Nine, Appendix when driving straight down the road under brak- for a Toe measurement field check method. ing, free wheeling, and power conditions.

Insufficient caster reduces stability and can cause wander. Excessive caster increases steering CAMBER effort and can cause shimmy. Either of these conditions may also have a detrimental effect on tire Camber is the angle formed by the inward or wear. Caster is adjustable with shims. Adjusting outward tilt of the wheel referenced to a vertical only one side is not recommended. Caster on both line. Camber is positive when the wheel is tilted sides should be equal or not more than 1⁄2 degree outward at the top, and negative when the wheel is difference. Generally, the vehicle will pull to the tilted inward at the top. Excessive positive camber side with the least positive caster. may cause smooth wear on the outer half of the tire tread. Excessive negative camber may cause wear on the inner half of the tread. Positive static- unloaded camber angles are built into the static- unloaded axle and put the loaded tire perpendicular to the road. Steer axles with positive camber and steer axles with negative camber are both available in the market. Studies have shown that slightly negative camber in long haul applications reduces irregular tire wear and allows higher EXTENDING TIRE LIFE removal mileage. Generally, the vehicle will pull to Section Three the side with the most positive camber.

Camber correction by bending axles is NOT RECOMMENDED by Michelin. Consult the axle manufacturer if camber is found to be incorrect (outside manufacturer specification).

Positive Camber Positive Caster + 0° - Negative Caster

STEER AXLE SETBACK (STEER AXLE SKEW)

Any measured deviation left (negative) or right (positive) away from perpendicular to the centerline of the vehicle is called the setback.

Top View

CASTER

Positive (+) caster is the backward tilt at the top of the kingpin when viewed from the side. Negative (-) caster is the forward tilt of the top at the kingpin when viewed from the side.

28 TANDEM AXLE PARALLELISM TMC RECOMMENDED ALIGNMENT TARGETS Tandem axle parallelism is critical because it can have a detrimental effect on all ten tires on the (Value representing industry-established tractor. Non-parallel drive axles tend to push the midpoint) tractor into a turn in the direction that the axle ends are closest. In order for the vehicle to go straight, Steer Axle: the driver must correct by steering in the opposite Toe: +1⁄16" Toe-in direction. The vehicle can then go straight, but all (0.08 degrees, 0.06 inches, 1.5 mm) ten tires are at an angle to the direction of travel that Camber: Less than 1⁄4 degree causes scrubbing. Excessive tandem axle non-par- Caster: Left +3.5 degrees allelism is usually detected in steer tire wear. If one Right +4.0 degrees steer tire is scrubbing from the outside inward and Setback: 0 degrees / 0 inches the other steer tire is scrubbing from the inside outward, then tandem axle alignment is suspect. Drive, Trailer and Dolly Axles A Thrust Angle (Square): 0 degrees / 0 inches Scrub (Parallelism): 0 degrees / 0 inches Top View Lateral Offset: 0 degrees / 0 inches

TOE-OUT-ON-TURNS

(Turning Radius)

Toe-out-on-turns is the difference in the arcs described by the steering tires in a turn. The pur- Vehicle Pulls to Left B pose is to prevent the inside tire from scrubbing around a turn since the outside tire (loaded tire) determines the turning radius of the steer axle. This is the Ackerman Principle. Improper geome- Section Three THRUST ANGLE (TRACKING) try results in wheel scrub in turns, which generally appears as toe wear on the tire. More specifically, EXTENDING TIRE LIFE The relationship of the geometric centerline of Ackerman wear shows itself as a rounded edge the vehicle and the direction that the axle points radial feather wear across the tread area of the tire. generates a thrust angle. Ideally this relationship This angle is more important on a city vehicle with would result in a 0 degree value when the axle cen- its many turns than on a line haul unit. terline is perpendicular to the geometric center line. However, any deviation from this setting will Ackerman geometry is dependent upon the increasingly cause the vehicle to travel away from steering axle track-width and wheel base of a vehi- the straight line, causing the tires to “dog track” cle. When the turning angle or wheel base changes and scrub. Tracking to the right generates a posi- from the original specification, Ackerman is affected. tive thrust angle; tracking to the left creates a negative thrust angle. Steering Arms

Top View Cross Bar (Tie Rod) Chassis C L Wheel Base

Rear Axle CL Center of Rotation

Basic Ackerman Steering Diagram 29 Toe and Axle Parallelism. Other fleets establish PERIODIC ALIGNMENT CHECKS permanent records, make adjustments more easily, An aggressive alignment preventative mainte- have more information for trouble-shooting, and nance program should include the following peri- obtain excellent results with the more expensive odic checks: equipment. The common ground is that the person using the equipment understands it, uses it 1. Upon delivery of new vehicles. Even properly, and follows the procedures consistently. though OEMs make a concerted effort to properly align vehicles at the factory, shifting and Michelin developed the Bib Alignment System settling can occur during delivery. Camber and to provide a highly portable system that combines caster may not change much, but Toe and some of the best aspects of simplicity while still Tandem Axle Parallelism may change suffi- providing PC-based adjustment calculations and a ciently to set up undesirable tire wear patterns “print out” permanent record. The Bib Alignment if not corrected upon receipt. System is an excellent tool for measuring and adjusting axle parallelism. It does not measure 2. At the first maintenance check. Post caster, camber or toe. break-in alignment checks should be done between 15,000-30,000 miles but no later than Heavy truck alignment has evolved to a precise 90 days after the first in-service date. If shifting science. The “field check” techniques may be used and settling did not occur during delivery, it may to detect a problem condition, but are NOT recom- occur during the first few thousand miles of mended for making adjustments/corrections. operation. Many OEMs recommend retorquing Proper alignment equipment should be used if a suspension/frame components after a few thou- decision is made to complete this service. sand miles of operation. A thorough alignment EXTENDING TIRE LIFE check should be made during this inspection Section Three (after the retorquing). Consideration should be AXLE PARALLELISM AND TRACKING given to different torque requirements on metric and standard bolts. In the straight-ahead position, the rear wheels 3. When new steer tires are installed or of a vehicle should follow the front wheels in a par- front-end components are replaced. allel manner. Wheels that are out-of-track can The steer tires coming out of service can tell a cause excessive tire wear. Failure of the wheel to story of good or bad alignment. With this feed- track is usually due to the following causes: back, an alignment program can continue to a. Master spring-leaf broken improve. Without feedback, the best an align- b. Worn springs ment program can do is stay at its current level. c. Auxiliary leaves broken d. Loose “U” bolts 4. When tire wear indicates a concern. e. Incorrect or reverse springs “Reading” tire wear can help identify alignment f. Bent frame issues. Unfortunately, correcting the alignment g. Locating rods or torque rods improperly does not necessarily correct the tire wear pat- adjusted tern once an undesirable wear pattern has been h. Locating rod or torque rod bushings worn established. excessively

Failure of the wheels to track is usually quite ALIGNMENT EQUIPMENT visible when one follows the vehicle on the highway. It is possible that, due to one of the above Alignment equipment exists that ranges from causes, no uneven wear manifests itself on the rear simple and inexpensive to sophisticated and costly. tires but an uneven wear pattern may show itself One factor that is common to all types of alignment on the front tires. This is because rear tires may equipment is that the person using it is extremely push the vehicle off course and give some toe-out- important to the resulting tire and vehicle perfor- on-turns in the straight-ahead position to the front mance! Calibration is another critical factor in tires. Hence, the driver makes a correction to offset maintaining the accuracy of the system – follow the steering action caused by the rear wheels. manufacturers recommendations. Some fleets have obtained excellent results with a good “scribe If the REAR axle of a vehicle is not at right angles and trammel bar” and paying strict attention to to the chassis centerline, the front tires are affected, 30 showing misaligned wear. In the diagram below, Schematic of the position of the rear axle of the vehicle has been Measurement Details altered because of a weakened left side spring – so X = X' Y = Y' that the rear axle on the left side is further from the AD = BC front axle than the rear axle on the right side. DE = CF

Top View

Inside Wear

Springs Springs

Outside Wear E Vehicle Pulls to Right X' Toe-out on turns at these steer angles is not equal to zero. F X In this diagram, the rear axle causes its wheels to point to the left side so that the rear end of the vehicle is, in fact, self-steered in that direction. The D vehicle would then steer itself to the right – unless the driver takes corrective action. If the driver Y' A C wishes to travel straight ahead, he will naturally Y compensate by turning his steering wheel. This action of the driver introduces toe-out-on-turns as B though the vehicle were making a turn. The vehicle is not going around a turn; it is moving in a straight line – because the front wheels are toed- out. Misalignment wear patterns on the front tires

may be apparent for this reason even though the Section Three front wheel alignment settings may be correct. EXTENDING TIRE LIFE How to Check Axle Parallelism and Tracking:

With the vehicle fully loaded and relaxed on a flat surface, select two points on the front and rear axles. These two points on each axle must be equal distance from the chassis center (e.g., at the point where the springs meet the axles). Using a plumb line, mark four points on the ground, move the vehicle away and measure the distance between the marks as shown on the diagram. E If AD = BC and DE = CF, the axles are parallel. If X = X’ and Y = Y’, the wheels are symmetrical or tracking. The Trailer Manufacturers Association X' recommends no more than 1⁄16 inch between axle ends and 1⁄8 inch maximum from the trailer king X pin to the lead axle ends. If no other defect can be Schematic of D Measurement Details found, misalignment wear can only be attributed to X = X' such errors in parallelism or symmetry as may exist. Y = Y' Y AD = BC A A more detailed field type procedure is recom- C mended by Michelin and can be found in Section Y' Nine, Appendix under Vehicle Alignment –

ATTACC PLUS system on Page 60-61. B 31 TIRE WEAR PATTERNS DUE TO MISALIGNMENT

It should be noted that some wear patterns might be from multiple causes. Additional information may be obtained in the TMC RP 216 Radial Tire Conditions Analysis Guide and Michelin Videos: Fundamentals of Tire Wear and Scrap Tire Analysis.

Camber Wear – If the axle has excessive camber, the tire will scrub off that shoulder. Pure camber wear is not seen when camber values are less than 1 degree. EXTENDING TIRE LIFE

Section Three Toe Wear – The typical wear pattern that develops from excessive toe is a feather edged scuff across the crown. Excessive toe is usually seen on both steer tires.

Cupping Wear – Any loose or worn component in truck steering or suspension systems can cause odd wear, cupping, and flat spots. Check for loose wheel bearings, steering gear lash, worn tie rod ends and king pins. Check for possible mis-mount conditions.

Free Rolling Wear – Wear at the edge of a rib circumferentially, which may or may not affect the entire rib widths. Intermittent side forces due to wheel assembly instability cause contact pressure Flat Spotting Wear – Localized wear across variations, resulting in this type of wear. Generally, the tread width. Causes include brake lock, brake due to excessive looseness in the suspension imbalance, out of round brake drums, axle hop or and/or steering components, this is also found in skip. A tire being parked on a surface containing slow wearing positions at high mileage. hydrocarbon oils, chemicals, and solvents can also Insufficient caster and excessive lateral tire/wheel cause this type of wear pattern. The affected area of runout also are contributing factors. the tread will wear more rapidly, leaving a flat spot. 32 one or more wheel positions locking up and flat spotting the tires.

4. Brake drums with balance weights thrown may result in diagonal wear.

5. Brake lock (flat spots) conditions may be evidence of deficiency in the Anti Lock Brake System.

SUMMARY OF TIRE ISSUES DUE TO BRAKES

Problem Possible Causes Result

Brake Heat 1. Overuse on down Bead damage to Diagonal Wear – Localized wear diagonally grades due to the tire ranging across the tread width. Side forces imposed by a improper gear. from simple distortion to 2. Brake dragging due combination of toe and camber create diagonal complete to mis-adjustment. stress in the footprint of the tire. Localized wear unwrapping of patterns tend to follow this same direction creating 3. Repeated stops the casing from without cooling the bead wire. diagonal wear. Causes include tandem in front of time. axle misalignment, excessive toe setting, axle misalignment, excessive steering system elasticity, Lock Up 1. Out-of-round Flat spots and incorrect steering angle in turns, and excessive brake assembly. odd wear. camber setting combined with high toe setting. 2. Slow release valves. Braking Systems and Issues: 3. Mis-adjustment slack adjusters. Air brake issues as they apply to tire wear and damages can result from imbalance or component concerns.

Distorted, brittle and/or discolored rubber in the bead area are signs of the “outside to inside” break- Section Three down of rubber products as a result of seating on a EXTENDING TIRE LIFE wheel surface which is heated to a temperature beyond the limit that the rubber products can toler- ate. This damage starts at a temperature in the mid- 200 degree Fahrenheit range, with accelerated damage occurring above the 300 degree Fahrenheit range.

1. Brake imbalance can be the result of the air system, including valves, not actuating the brakes simultaneously. This may be the result of dirt, Brake Heat leaks and/or valve cracking pressure.

In a tractor/trailer combination, the more rapid brake application time now being used (up to twice as fast as pre FMVSS-121 systems) can result in a brake imbalance due to combinations of old tractors with new trailers or new tractors with old trailers.

2. Component situations, such as out-of-round brake drums or unevenly worn brake shoes, also result in tires acquiring odd wear and flat spots.

3. Another source of brake imbalance is the improperly adjusted slack adjuster. Any of these brake imbalance situations can result in Lock Up 33 5th Wheel Maintenance and Placement: proper operating position on the road. If the suspension is in good operating order, the tires will Placement of the 5th wheel can be determined track straight and be evenly loaded. This promotes by the need to properly distribute the load over the slow, even wear and low tire cost-per-mile. drive tandems and the steer axle for legal loads. It can also be placed to lengthen or shorten the over- Different truck manufacturers use different sus- all length of the tractor-trailer unit. However, with pension systems. Some of these are adjustable for sliding 5th wheels, many drivers place the 5th wheel making minor changes, and some are not to give the smoothest ride and easiest steering. The adjustable. All suspensions have parts that move placement and movement of the 5th wheel can and are, therefore, subject to wear. Worn or broken change the tire loading substantially, causing tire suspension parts are one of the main causes of overload or tire underload conditions. Insufficient irregular tire wear and handling concerns. (Ref. – lubrication of the 5th wheel is a major cause of Quick Checks for Suspension and System Faults on poor vehicle handling. next page.) When observing irregular wear on a tire, first check for worn or broken front and rear sus- A 5th wheel in the most rearward position, pension parts. combined with stiff front axle springs can cause the front tire to periodically unload, leading to vehicle As suspensions move away from multiple shimmy and irregular tire wear. Vehicle manufac- springs, there is an increased need to dampen the turers usually recommend a fifth wheel placement effect of road shock, increasing the need for func- that results in payload transfer to the front axle. tional shock absorbers and their related bushings Improper front axle load distribution can adversely and parts. Shocks should be properly mounted to affect braking and handling, which can result in insure proper dampening is achieved. Refer to excessive tire wear.

EXTENDING TIRE LIFE TMC RP 643 Air-Ride Suspension Maintenance Guidelines on air suspension systems. Section Three Suspensions: Replacement guidelines are indicated as 150,000 in Forming the link between the truck and the tire, a highway vocation and 100,000 in a regional voca- the suspension system provides a very important tion. Additionally, worn bushings result in move- contribution to tire performance. The suspension ment when in a dynamic state and can lead to must support the load and maintain the tire in the irregular tire wear.

34 QUICK CHECKS FOR FRONT SUSPENSION FAULTS

SYMPTOM POSSIBLE CAUSE Thumps and Knocks from Front Suspension • Loose or worn ball joints • Loose front suspension attaching bolts • Missing adjusting shims • Loose shock absorber mountings • Check spring eye bushings Groans or Creaks from Front Suspension • Loose attaching bolts • Bent control arm or steering knuckle • Worn kingpins or kingpin bushings Squeaks from Front Suspension • Coil spring rubbing on seat Wander or Shimmy • Worn tie rod ends • Worn kingpins or kingpin bushings • Loose suspension attaching bolts • Weak shock absorbers • Weak front springs • Incorrect front end alignment Frequent Bottoming of Suspension on Bumps • Weak front springs • Weak shock absorbers Front End Sag • Weak front springs Irregular or Excessive Tire Wear • Incorrect front wheel alignment • Worn kingpins or kingpin bushings • Loose front suspension attaching bolts • Weak shock absorbers • Weak front springs • Bent control arm or steering knuckle • Worn tie rod ends • Excessive steering system compliance Section Three Floating, Wallowing and Poor Recovery from Bumps • Weak shock absorbers

• Weak front springs EXTENDING TIRE LIFE Pulling to One Side While Braking • Worn kingpins or kingpin bushings • Loose suspension attaching bolts • Bent control arm or steering knuckle • Weak front springs • Weak shock absorbers Rough Ride and Excessive Road Shock • Damaged shock absorbers • Weak shock absorbers • Weak springs • Control arm shaft bushings need lubrication • Worn kingpins or kingpin bushings Excessive Steering Play • Worn kingpins or kingpin bushings • Loose suspension attaching bolts • Worn control arm shaft bushings • Weak front springs • Worn tie rod ends Pulls To One Side • Worn kingpins or kingpin bushings • Loose suspension attaching bolts • Worn control arm shaft bushings • Weak front springs • Incorrect wheel alignment • Bent control arm or steering knuckle Hard Steering • Worn kingpins or kingpin bushings • Incorrect front end alignment • Bent control arm or steering knuckle

35 QUICK CHECKS FOR REAR SUSPENSION FAULTS

SYMPTOM POSSIBLE CAUSE Shock Absorbers • Improperly installed mounts and/or bushings • Damaged or leaking shocks U-Bolts • Not torqued to specification • Improperly torqued due to mismatched metric and standard bolts with different specifications Suspension System • Loose attaching bolts • Worn bushings in shocks, spring hangers, torque rods • Missing alignment adjusting shims • Excessive drive axle offset • Excessive sway bar movement • Worn hanger pins allowing axle movement • Improperly functioning ride height control system Wheels out of track (dog tracking) • Master or auxiliary spring-leaf broken • Incorrectly installed springs • Worn springs • Loose "U" bolts • Bent frame • Torque rods improperly adjusted • Torque rod bushings worn excessively

EXTENDING TIRE LIFE Alignment • Incorrect parallelism, skew, scrub

Section Three • Dual position toe-in or out • Camber Miscellaneous • Wheel bearings loose or damaged • 5th wheel placement • 5th wheel and chassis lubrication

QUICK CHECKS FOR TRAILER SYSTEM FAULTS

SYMPTOM POSSIBLE CAUSE Quick checks for trailer system faults would include: • Slider assembly movement, loose attaching bolts • Air-ride suspension movement • Insufficient lubrication • Worn shocks or springs • Alignment (toe, camber, parallelism) • Worn or loose wheel bearings • Brake imbalance • Slow release of trailer brake systems • Operational conditions, high scrub application • Tire scrub/dragging at dock deliveries • Air pressure maintenance (improper for operation) • Overloaded/underinflated, high speed empty hauls • Mismatched pressure by dual position or axle • Mismatched tread depth/tire design by dual position • Improper tread depth for application/operation • New steer tire(s) mixed in trailer positions • Tire rotated from steer or drive with existing wear • Improper tire assembly mounting • Driving habits, improper use of trailer brakes

36 Section Four EXTENDING THE TIRE LIFE

A 10 psi incremental change in tire inflation will ® X ONE AIR PRESSURE alleviate most wear forms derived from vehicle MAINTENANCE PRACTICES anomalies, driver influence and/or application. Always refer to actual axle loads to determine Tire pressure maintenance advice for users of the initial recommended cold inflation pressure. the new Michelin® X One® wide single truck tires (445/50R22.5 LRL and 455/55R22.5 LRL) Cold inflation pressures must not be lower than indicated in the tables above for actual axle loads. The Michelin® X One® family of truck tires is designed to replace dual assemblies on drive and For example, the 445/50R22.5 X One® XDA® trailer positions in over-the-road applications. tire, load Range L (20 ply) tires have a maximum air Proper air pressure maintenance is critical to pressure of 120 psi (cold) with a weight carrying obtain optimized performance from these tires. capacity of 20,400 lbs. per axle. If the tire is mount- Due to the unique casing design of the Michelin ed on a vehicle carrying 17,640 lbs. per axle, the X One tire, traditional air pressure adjustment appropriate air pressure is 100 psi (cold). Refer to practices for dual tires may not apply to Michelin the Michelin Tire Data Book and Technical X One tires. In order to ensure optimized perfor- Bulletins for appropriate recommendations. (See mance of these tires, Michelin North America offers Introduction for list of data books.) the following guidelines: For trailers equipped with an air pressure moni- 1) Cold inflation pressure should be based on max- toring system, system pressure should be regulated imum axle load in daily operation. Cold inflation based on the maximum load the axle will carry and pressures must not be lower than indicated in be at the cold equivalent for this load. the tables below for actual axle loads. For additional information please consult the Michelin In equivalent sizes there will be no required Data Book — Truck Tires, Retreads, and change in gear ratios nor any required component Commercial Light Truck Tires (MWL40731). changes. Consult your equipment manufacturer for details. Contact Michelin directly for any varia- 2) If rapid or irregular wear develops, please refer tion in specification. to the chart below for diagnostic steps: EQUIVALENT X One® SIZES Application Location Possible Cause on the Tire Dual Size X One® Size Shoulder Pressure too low 11R22.5 or 275/80R24.5 455/55R22.5 Trailer Tires Center Pressure too high 275/80R22.5 445/50R22.5

Shoulder Pressure too high ® Drive Tires Center Pressure too low X ONE

445/50R22.5 LRL Section Four LOAD PER AXLE MAX LOAD PER TIRE* psi 70 75 80 85 90 95 100 105 110 115 120 125 psi 120 kPa 480 520 550 590 620 660 690 720 760 790 830 860 kPa 830 S 13260 14000 14740 15480 16200 16920 17640 18340 19020 19720 20400 S 10200 lbs. lbs. D D S 5960 6360 6660 7040 7320 7700 7980 8260 8620 8900 9250 S4625 kg. kg. D D 455/55R22.5 LRL LOAD PER AXLE MAX LOAD PER TIRE* psi 75 80 85 90 95 100 105 110 115 120 125 130 psi 125 kPa 520 550 590 620 660 690 720 760 790 830 860 900 kPa 860 S 14620 15400 16160 16920 17660 18400 19140 19860 20600 21200 22000 S 11000 lbs. lbs. D D S 6680 7000 7400 7700 8100 8380 8680 9060 9340 9720 10000 S5000 kg. kg. D D

37 WHEELS: 91.5" 74.5" The X One® tires require the use of 22.5 X 14.00" Track wheels. The majority of the wheels currently offered have a 2" outset, or offset. Outset is the distance from the mounting surface of the wheel to the centerline of the rim, when the rim centerline is mounted outboard of the hub face. Thus a wheel with a 2" outset has the centerline of the rim base 2" outboard from the hub mounting surface.

Some axle and hub manufacturers have recent- ly clarified and confirmed their position concerning the use of such wheels with their respective components. While the position of the component 2" 17.1" manufacturers is not totally consistent, the majority’s view concerning the retrofit of duals with X One tires can be summarized as follows: 95.5" AXLE TYPE* SPINDLE WHEEL 71.5" TYPE RECOMMENDATION Track Drive axles "R" 2" outset wheels 47" Trailer axles "P" 2" outset wheels Trailer axles "N" Check with component manufacturer * Many other axle and spindle combinations exist. Contact axle manufacturer.

Truck and trailer manufacturers may have different specifications. For optimum track width, stability and payload, end-users should talk to their trailer suppliers about the use of 83.5" axles with zero outset wheels. New wheel bearing products 6.5" 11" may be available at OEM and replacement, check with appropriate manufacturer.

MOUNTING INSTRUCTIONS: Section Four

X ONE VEHICLE TRACK: The X One tire must be mounted on 22.5 x With a standard length axle and 2 inch outset 14.00" size wheels. Both Steel and Aluminum are ® wheels, the resulting variation in track width is an available in Hub (Uni Mount) piloted and currently increase of approximately 1.5 inch per side (3 inch- Aluminum is available in Stud (Ball Seat) configura- es total) as compared to a dual tire configuration. tion. Supplemental parts will be required with 'Stud-Piloted' wheels: Front and rear outer cap nuts End-users that have retrofitted vehicles with 2" to replace inner and outer nuts used for mounting outset wheels should contact their respective traditional stud-piloted dual assembly. Industry vehicle, axle or component manufacturers for spe- wide part numbers will be 5995L and 5995R. There cific application approvals or maintenance rec- are no differences in mount or dismount proce- ommendations. dures other than when mounting the X One tire onto a vehicle, position the tire so that the tire sits Measurements are rounded. on the outbound side of the wheel similar to where the outer dual would normally be positioned. Additionally, this will offer exceptional lateral clearance. Select a valve stem that can be accessed for air pressure checks and is installed facing outward.

38 Note: Safety cages, portable and/or per- CHAINS: manent, are also available for inflation ® of the X One tire assemblies. Specific chains are available for the X One product line. Consult Michelin for proper type/size.

GEAR RATIO:

A change in tire dimension will result in a change in engine RPM at a set cruise speed* that will result in a change in speed and fuel economy. The effect of tire size change on gear ratio should be considered in individual operations: •A decrease in tire radius will increase startability

CORRECT PLACEMENT INCORRECT PLACEMENT tractive torque and decrease geared and indicated top speed. • An increase in tire radius will reduce tractive torque and increase top geared speed. Note: Use of outset wheels may change • RPM/SPEED/SIZE: These factors can effect RPM Gross Axle Weight Rating (GAWR), consult if corresponding changes are not made to engine vehicle and component manufacturer. ratios. Example: 11R24.5 XDA-HT (471 rpm) versus 455/55R22.5 XDA-HT (494 rpm). 471/494= .953, .953 X 60 mph = 57.21 mph REPAIR AND RETREAD: * Exceeding the legal speed limit is neither recommended nor endorsed. For information on proper repair/repair procedures and damage limits on the X One tire product line, please consult Michelin for technical guidance. ® X ONE Section Four

39 CONTACT AREA/FOOTPRINT:

X One® XDA® versus P22.5 XDA2® (below). All drawings 0.4 : 1 Scale.

Unloaded - 8,500 lb/axle

Loaded - 17,000 lb/axle

Unloaded - Unloaded - 8,500 lb/axle 8,500 lb/axle Section Four X ONE Loaded - 17,000 lb/axle Loaded - 17,000 lb/axle ®

TIRE AXLE PRESS LOADED FOOTPRINT FOOTPRINT TOTAL CONTACT TOTAL % OF LOAD (psi) SECTION LENGTH WIDTH FOOTPRINT SURFACE CONTACT 2 DUALS (lbs) WIDTH AREA RATIO AREA mm mm mm mm sq mm sq mm 445/50R22.5 X One XDA 17,000 105 459 201 376 69,400 x 0.686 = 47,600 0.98 275/80R22.5 XDA2 17,000 105 297 200 216 39,450 x 0.616 = 24,300

455/55R22.5 X One® XDA-HT™ 17,000 100 472 227 385 74,350 x 0.697 = 51,800 0.95 11R22.5 XDA-HT™ 17,000 100 304 204 216 41,250 x 0.674 = 27,800 275/80R24.5 XDA-HT 17,000 100 298 206 215 40,750 x 0.670 = 27,300

40 Section Five REPAIRS

For more information on repair procedures, For information on proper repair procedures refer to Michelin Commercial Truck (Radial) Tire and damage limits on the X One® tire product line, Nail Hole Repair Manual (MWT 40163). please consult Michelin for technical guidance. REPAIRS

Michelin® truck tires are often scrapped even • Broken or deformed bead wires. though they could give many more miles of service • Ruptures, creases, or detachment of radial ply too by being properly repaired. Procedures for the great in length. (See table of repair limits.) proper repairing of Michelin truck tires are con- To repair tires with any one of these conditions tained in the Michelin Commercial Truck (Radial) would result in a tire that would not be safe for fur- Tire Nail Hole Repair Manual. ther use.

Only personnel specially trained and equipped Point E to Point F to perform these kinds of repairs should do repairs. Improperly repaired tires are dangerous and can Sidewall and crown damages can be made to cause tire destruction, property damage and per- both steel and rubber. Point E to point F is restricted sonal injury. to repairs of rubber damage only with the exception This section explains how to inspect a tire to see if of larger Michelin Truck tires. In these, repairs may it can be repaired, contains tables indicating allow- be made for chafer strip damage as well as rubber- able repair limits, identifies the applicable patches to only damages. The measurement of which varies be used and explains how to repair punctures. according to tire size. See pages 42 - 43 for limits.

INSPECTION FOR REPAIR

A properly made repair can help provide many additional miles of wear to an otherwise useless E E tire. However, the tire must be carefully inspected to determine whether its condition justifies the cost E E of repairing, and if it can be safely reused under F F F F normal operating conditions. MAXIMUM INJURY SIZE (Sidewall) Careful inspection is mandatory in the repair of radial tires. They should be checked thoroughly on 130 x 20 mm 1 3 (5 ⁄8" x ⁄4") a well-lighted spreader capable of completely revealing all damages, both inside and out. 100 x 30 mm 1 (4" x 1 ⁄4") The finished repair should permit the tire to be reused in the type of service for which it was 80 x 40 mm 1 1 designed without limiting its future retreadability. (3 ⁄8" x 1 /2") Naturally, the performance of any tire will depend MAXIMUM INJURY upon the conditions of use and the care with which SIZE (Crown) it is operated and maintained. As a general rule, never repair tires with: • Damage caused by being run flat or underinflat- 40mm ed (wrinkling, corrugations, dislocations, abra- 1 sions on the interior). (1 ⁄2") •Damages beyond repair limits. REPAIRS

• Sidewalls with noticeable creasing of radial ply Section Five (light truck).

41 MEASURING DAMAGES

1. Radial Ply Damage: 2. Crown Ply Damage: The size is measured within a rectangle: The size is determined by the maximum L = Length of damage along the cords. diameter of the damage measured on the W = Width of damage across the cords. innermost (crown) working ply.

Diameter

REPAIR LIMIT ALLOWABLE REPAIR LIMITS AND APPLICABLE PATCHES:

REPAIR LIMITS - TRUCK TIRES (Millimeters Shown in Parentheses)

TIRE ERX SL 41 ERX SL 43 ERX SL 45 CROSS E.F. SECTION ZONE CROWN L x W CROWN L x W CROWN L x W

1 2 ⁄2" 8R 3 1 (65 mm) 2 ⁄4" x 1 ⁄2" 3 3 8.25R 235/80R 2 ⁄8" x ⁄4" (70 mm x 40 mm) (60 mm x 20 mm) or 8.5 245/70R 1 1 or 3 ⁄8" x 1 ⁄4" 9R 255/70R 3 5 2 ⁄4" x ⁄8" (80 mm x 30 mm) 9.00R 255/80R 3 ⁄4" (70 mm x 15 mm) or 10R 265/70R 3 3 1 1 (20 mm) or 4 ⁄8" x ⁄8"3⁄8" x 1 ⁄2" 10.00/90R 275/70R 1 3 3 ⁄8" x ⁄8" (110 mm x 20 mm) (80 mm x 40 mm) 10.00R 275/80R (80 mm x 10 mm) 1" or or 11R 285/70R 1 3 1 1 3" (25 mm) 5 ⁄8" x ⁄8"1⁄2" 4" x 1 ⁄4" 215/75R 295/80R (75 mm) (130 mm x 10 mm) (40 mm) (100 mm x 30 mm) 225/70R or 1 3 5 ⁄8" x ⁄4" 11.00R 18R 3 1 1" x ⁄4"2⁄8" x 1" (130 mm x 20 mm) 12R 305/70R (25 mm x 20 mm) (55 mm x 25 mm) 12.00R 305/75R 5 ⁄8"or or 13R 315/80R 1 5 3 3 (15 mm) 1 ⁄2" x ⁄8"2⁄4" x ⁄4"

Section Five 13/80 365/80R (40 mm x 15 mm) (70 mm x 20 mm) REPAIRS 13.00R 385/65R or or 14/80R 425/65R 3 3 3 5 2 ⁄8" x ⁄8"3⁄4" x ⁄8" 14.00R 445/65R (60 mm x 10 mm) (95mm x 15mm)

NOTE: The patches listed above are for rim diameter sizes of 17.5" through 24.5". For 15", 16" and 17" light truck tires see "Repair Limits: Light Truck" on Page 43.

42 REPAIR LIMITS: LIGHT TRUCK

MAXIMUM LIMITS BY PATCH SIZE MICHELIN E.F. CROWN PLIES RADIAL PLY PATCH TIRE CROSS SECTION ZONE DIAMETER LENGTH x WIDTH SIZE

3 1 3 30x9.50R15 LT215/75R15 LT235/85R16 ⁄8"1⁄4" x ⁄8" ERX SL-21 1 3 31x10.50R15 LT235/75R15 7.50R16 (10 mm) (30 mm x 10 mm) 4 ⁄8" x 2 ⁄4"

1 3 3 3 32x11.50R15 7.00R15 8.75R16.5 2 ⁄8" ⁄4"2⁄4" x ⁄4" ERX SL-23 1 3 33x12.50R15 LT225/75R16 9.50R16.5 (55 mm) (20 mm) (70 mm x 20 mm) 6 ⁄8" x 2 ⁄4" LT195/75R15 LT245/75R16 7.50R17 1" 2" x 1" ERX SL-41 LT205/75R15 LT215/85R16 1 (25 mm) (50 mm x 25 mm) 7 ⁄2" x 4"

3 1 3 7.00-16 ⁄4"1⁄2" x ⁄4" ERX SL-21 1 3 7.50-16 (20 mm) (40 mm x 20 mm) 4 ⁄8" x 2 ⁄4"

3 3 3 3 7.50-17 2 ⁄8" ⁄4" 2 ⁄4" x ⁄4" ERX SL-23 1 3 8.00R16.5 (60 mm) (20 mm) (70 mm x 20 mm) 6 ⁄8" x 2 ⁄4" 8.75R16.5 1" 2" x 1" ERX SL-41 9.50R16.5 1 (25 mm) (50 mm x 25 mm) 7 ⁄2" x 4" NOTE: Section repairs are not recommended for LT 14" rim diameter. The economics are not favorable, and the finished product seldom produces customer satisfaction.

SECTION REPAIR LIMITS: SPLIT REPAIRS

MAXIMUM LENGTH OF SPLIT ALONG RADIAL PLY NO. CORDS TIRE CROSS SECTION DAMAGED ERX SL-21 ERX SL-23 ERX SL-25

6.50 8.5 275 3 1 3 ⁄4"1⁄2"2⁄8" 2 79 295 (20 mm) (40 mm) (60 mm) 7.50 9.5 1 1 3 1 ⁄2"3⁄8"4⁄4" 810 1 8.25 (40 mm) (80 mm) (120 mm)

1 1 3 11.00 13.00 315 1 cord only 1 ⁄2"3⁄8"4⁄4" 12.00 14.00 for these sizes (40 mm) (80 mm) (120 mm)

REPAIR LIMITS: BEAD AREA (Anywhere in the bead area see EF Zone in diagram on page 41.)

RUBBER ONLY DAMAGES W Minimum Distance Between Repair Quantity – All Applications 150 mm 75 mm 4 per bead 8 per tire RUBBER ONLY DAMAGES Location L x W Minimum distance Between Damages Application Bead Toe 2 mm x 50 mm 75 mm SEVERE USE No Damage to Bead Seat 8 per tire No Damage to Chaffer CHAFTER STRIP DAMAGES L x W Minimum Distance Between Repair Quantity – All Applications 25 mm x 55 mm 75 mm 4 per bead 8 per tire

L = length in radial direction REPAIRS

W = length in circumferential direction Section Five NOTE: No repair to BODY PLY are permitted inside or outside of the tire in the area within a radial direction of 75 mm from the bead point (see area EF). 43 PUNCTURE REPAIRS

Punctures in the crown up to 1⁄4" (6 mm) in Inspect the tire thoroughly, inside and out, for diameter and up to 1⁄8" (3 mm) in the sidewall are secondary damage or evidence of run flat damage to be repaired by filling the hole with a rubber that may result in the need for a major repair or to based compound and placing a rubber radial repair scrap the tire. unit on the inside of the tire. Injuries larger than 1⁄4" (6 mm) in the crown and 1⁄16" (2 mm) in the sidewall must be processed in a full service repair shop using approved section repair methods.

Notes: Puncture and section repairs may be made in all areas of the tire. The bead area (E-F zone) is a rubber repair only area.

Crown

E-F Zone Size

Sidewall Passenger 1 Car 2 ⁄8" Light 1 Truck 2 Sidewall 2 ⁄ " E E Truck 3" (INTERIOR DAMAGE CAUSED BY NAIL) FF

Dip a blunt probe in self-vulcanizing solution External, or outside-in, repair methods using for lubrication and to coat the walls of the hole. sealants, string, rubber bands or rivet-type plugs is prohibited. The tire must be demounted and Do not use sticklebacks or rasping devices for inspected for possible internal damage. probing, as you may cause unnecessary enlarge- ment of the injury. The following steps are required to satisfactorily repair punctures in MICHELIN® radial tires: 1. Inspection 2. Cleaning 3. Wire Grinding 4. Select Repair Unit 5. Cementing Puncture Hole 6. Filling Puncture Hole 7. Buffing for Repair Unit 8. Cementing Buffed Area 9. Applying and Stitching the Repair Unit 10. Regrooving (if necessary)

1. Inspection:

Mark the location of the puncture with a tire

Section Five crayon and remove the puncturing object. After REPAIRS the tire has been removed from the wheel, it must Carefully probe the hole to determine its size be placed on a spreader that will open the beads and direction. Make sure all traces of the penetrat- fully without buckling or distorting the tire. ing object have been removed.

44 2. Cleaning: by using a cementing tool or small brush.

A liquid rubber cleaner/buffer must be used to If the hole is too small to allow cement to flow remove all traces of silicone lubricants on the into it freely, it is best left alone, as it should not be inside of the tire that will affect adhesion. Spray or enlarged needlessly. squirt the liquid onto the inner liner, and use a clean cloth or rubber scraper to obtain a uniform, clean dull black appearance. 6. Filling Puncture Hole:

A great variety of materials are available on the 3. Wire Grinding: market to fill puncture holes. These include, but are not limited to, Patch Plug Combination Units, If any damaged wire filaments protrude into the Headless Inserts, and A&B Compound. inside of the tire they must be ground off. Use a small pointed 1⁄8" diamond carbide burr mounted Use enough material to completely fill the in a low speed grinder (1200 rpm max) to grind the puncture and extend beyond the exterior of the ends flush with the liner surface. Wire cutters will tire. Material should be flush with the surface of the not cut close enough. Do not enlarge the hole tire both inside and out. unnecessarily. If an aluminum oxide stone is used to trim back damaged wire; it must be mounted in a high-speed (20,000 RPM min.) grinder.

Headless Rubber Inserts (Stems) or Patch Plug Combinations may be inserted in several ways. Refer to the individual supplier’s instructions for proper use.

Cut the insert off about 1⁄32" higher than the surface of the liner.

7. Buffing For Repair Unit:

4. Select the proper repair unit: Use a wire brush or a fine grit buffing wheel in a low speed grinder (less than 5,000 rpm) to buff the Center the unit over the puncture and outline an insert flush with the liner surface. Lightly buff the area 1/2 inch larger than the repair unit. area that the repair is to cover to an even velvet-like RMA-1 texture. Remove all traces of the venting 5. Cementing Puncture Hole: ribs in the repair area. Do not buff through the REPAIRS

Apply cement liberally into the puncture hole inner liner or expose any cords of the radial ply. Section Five

45 Remove all buffing dust and debris from inside With the beads of the tire relaxed in their normal the tire with a vacuum cleaner. Brush the buffed parallel position, center the patch over the hole and area with a hand held soft wire brush to remove all stitch it down thoroughly from the center outwards loose particles. to remove trapped air.

Use a corrugated stitcher to make sure that the edges are down tight without creases and folds.

*Check manufacturer’s instructions for cementing the repair.

Remove the transparent covering from the top of the repair unit.

Remount the tire to recommended pressure and check for leaks. (Refer to Section Two, Mounting the Tire when remounting the tire.)

8. Cementing Buffed Area:

Apply a liberal coat of cement to the buffed area. Move the puncture to the up position, i.e., 12 o’clock, to achieve even drying, as solvents are heavier than air.

Let dry 10-15 minutes depending upon humidity. 10. Regrooving (if necessary): Refer to the repair material supplier for pre- Please refer to Page 10 of this manual. ferred drying times. 9. Applying and Stitching the Repair Unit*:

Carefully remove the backing from the adhesive side of the repair unit, taking care not to touch the tacky surface. Section Five REPAIRS

46 Section Six RETREADING Section Six

For more information on retreading, refer to equipment for radial tires must be provided in the RETREADING Michelin MRT Tread Width Informational retread shop. The proper tread designs, tread Guide”(MYT41805). width, tread compound and tread depths, must be selected according to the type of tire and its antici- For information on proper retread procedures pated service. on the X One® tire product line, please consult Michelin for technical guidance. The tire must be processed with precision to maintain the design characteristics of the Michelin® radial. As there is very little margin for RETREADING error when retreading radial tires, perfection should be the only standard acceptable. The purpose of this section is to provide the retreader with the basic procedures required to For more information contact your local properly retread the Michelin® radial tire. Michelin Representative.

By itself, this section should not be considered as a guarantee for the proper processing of a retreaded tire, nor is it meant to be used as a substi- BUFF RADIUS tute for a regular training program. Charts giving radius specifications should be It has been designed to be used as a “working available and referred to on each tire. tool” for the new or inexperienced employee, or as a reference manual for the experienced person. The correct radius makes it possible to achieve the correct profile and an even distribution of the Since Michelin radial tires are manufactured to residual rubber covering the belt package. The very precise tolerances, it is necessary for similar amount of residual rubber (undertread) covering standards of accuracy to be maintained during the the belt package should be equal in depth across retreading process. Suitably designed modern the surface of the belt package. (Photo A)

Photo A: Equal undertread

Photo B: Too flat

47 RETREADING Section Six

Photo C: Too round

Too flat a radius can leave too much rubber on the shoulders of the tire. This leads to higher operating temperatures in the shoulder. (Photo B)

Too round a radius leaves too much rubber on the center of the tire. This leads to higher operating temperatures in the center. (Photo C)

After buffing, a radius template should be used to verify the buffed radius of the finished tire. (Photo D)

Photo D: Verify the radius on every tire

UNDERTREAD on every tire to verify that less than 3⁄32 of an inch The amount of residual rubber (undertread) of rubber remains. This can be done by making a covering the belt package should be equal in depth pilot skive (Photo F) or by using an electronic mea- across the surface of the protector belt. The suring device (Photo G). amount of remaining undertread should be less Too much undertread at buff makes for too than 3⁄32 of an inch. much undertread in the finished product. (Photo Too much undertread leads to higher operating H) Control each step. The total amount of under- temperatures. (Photo E) tread should be no greater than what the tire was designed to contain. The remaining undertread must be measured

Photo E: Excess Undertread

48 Section Six RETREADING

Photo F: Pilot skive Photo G: Electronic device

Photo H: Too much total undertread

BUFF WIDTH

Charts giving width specifications should be available and referred to on each tire.

The correct width makes it possible to achieve the correct profile that allows the design of the tire to evenly distribute stresses.

A tape measure should be used to verify the casing width after buffing each tire, but prior to trim. The largest possible tread should be used. (Photo I) Photo I: Measure for largest tread After choosing the correct tread, place a sample on the tire and mark the amount of shoulder trim needed. The amount of shoulder trim can be from 3/16” Trim no trim to a maximum trim of 3⁄16 of an inch per shoulder. The trim for mold cure can be up to 3⁄8 1/2” Trim of an inch per side, but the final cure dimensions should return the tire to within 3⁄16" per shoulder of the tires original width dimensions.

The shoulder trim angle should not create a trim length greater than 1⁄2 of an inch. (See illustration to the right.)

49 Section Seven COST ANALYSIS

1. Total mileage (considers new and retread COST ANALYSIS mileage for steer, drive and trailer) Each fleet operation is different, but there is one 2. Residual casing values or casing resale value consistent goal and that is to achieve the best possi- 3. Requirements of the specific wheel position ble operating cost. This section is designed to pro- (steer, drive and trailer) vide a guide to determining a Cost Per Mile (CPM). 4. Repairability (dollars spent on additional mounts and dismounts, repair time and labor) COST ANALYSIS

Section Seven The simplest CPM is found by dividing the price 5. Retreadability (additional casing purchases) of the tire and any retread by the total mileage. 6. Fuel efficiency (see section below) While this is an easy calculation, it is very mislead- 7. Total expected casing life ing by ignoring many of the added benefits of the 8. Labor (scheduled and unscheduled) tire or the transfer of residual casing value from one 9. Road call (by shop personnel as well as life to another. Emergency calls) 10. Disposal fees Determining CPM by wheel position could pro- 11. Liability Insurance vide an important gauge for performance since each wheel position is a very special case with unique An estimate of the CPM obtained by different operating requirements. Here are some of the key tires in different wheel positions is shown in the elements that need to be considered in any analysis: examples below.

STEER AXLE

a. XZA3™ New Tire Price (estimate) 350.00 b. Residual Casing Value (estimated) - 60.00 c. Total Miles (estimated) ÷ 120,000 d. CPM = $ .00241 per mile

DRIVE AXLE

a. XDA3™ New Tire Price (estimate) 350.00 b. Residual Casing Value (estimated) - 60.00 c. Total Miles (estimated) ÷ 250,000 d. CPM = $ .00116 per mile

YOUR OPERATION Steer Drive Trailer

a. New Tire Price ______b. Residual Casing Value ______c. Total Miles ______d. CPM ______

50 There is more to cost per mile calculations than the Michelin® X One® tire in drive and trailer posi- treadwear alone, for instance: tions can provide an increased 5% over these Advanced Technology tires.

In the same way, all other benefits derived from FUEL SAVINGS the use of Michelin radial tires impact the final cost per mile. Tires are a major component in the operating • Helps reduced downtime due to flats efficiency of the vehicle. The Michelin® tires with • Softer ride - greater payload and vehicle Advanced Technology are built to maximize energy protection conservation and can provide a fuel savings of 3% • Excellent retreadability and repairability to 9% compared to competitors’ radial tires. And

To calculate potential fuel savings: A. Cost of Fuel/Gal. $ ______B. Annual Miles ______C. MPG of the Vehicle ______mpg D. Total Estimated Fuel ______B ÷ C = gal ______E. % Fuel Savings % ______F. Estimated Fuel Savings (E x D) = gal______(F x A) = $ ______Section Eight TUBE TYPE TIRE

For a more in-depth calculation, consideration should be given to looking at the rolling resistance factors for the specific tires you are considering and ask for the assistance of your Michelin Representative in determining the savings. The next step would be to conduct a SAE Type 1376 fuel test and eliminate all the variables. Again, refer to your Michelin Representative for assistance.

51 Section Eight TUBE-TYPE TIRE

THE CROSS-PLY (OR BIAS-PLY) TUBELESS OR TUBE-TYPE? TIRE As shown below, there are considerable advantages to using tubeless instead of tube-type tires. Whether you choose tube-type or tubeless, Michelin has the tire to meet your needs. Some Michelin tube- type tires may be run with or without a tube. Contact Michelin to determine tires that apply.

TUBE-TYPE (Seven Components)

Cross-ply or conventional tires have a number of plies which are laid diagonally, criss-crossing one another. As the tire revolves and deflects, these crossed plies interact and generate heat – a process Locking Side Disc Flap Tube Tire TUBE TYPE TIRE

Section Eight that prematurely ages the components and short- Ring Ring Wheel and Valve ens the life of the tire.

The number of cross-plies in a conventional tire MICHELIN RADIAL TUBELESS TRUCK TIRES tends to stiffen its walls, preventing sufficient flex Tubeless – Simplified mounting requires three under heavy load. This causes lateral tread movement components. which impairs road grip and causes tread abrasion. • No tube and flap Definitions: • Less downtime due to flats. Fewer road delays • Fewer components Aspect Ratio: A nominal number, which repre- Mismatching of flanges and lock rings is eliminated sents the section height, divided by the section - No cracked rings or components width and expressed as a percentage - No bent or distorted parts Example: 10.00R20 Aspect Ratio = 10.00 • Slower rate of pressure loss from punctures • Cooler running ® Tube Code: The proper Michelin tube to be • Lower profile used with Michelin® tube-type tires is designated by the nominal rim diameter followed by a code. PROMOTES: Example: Tube for 10.00R20 Michelin is 20N. • Increased mileage – Michelin tubes are made of butyl rubber and Longer carcass life TUBELESS (Three Components) marked with the trade name “AIRSTOP®”. Because • Fuel savings of the extreme flexibility of the Michelin tire, it is rec- • Extra payload ommended to use an “AIRSTOP” tube. These tubes • Reduction in are made with an overlap splice that is stronger than labor and the butt splice used in many other tubes. inventory costs • Greater stability Flap Code: When a flap is required, the proper • Improved road size to use with Michelin tires on each particular rim handling is designated by a code, the last two digits of which • Lower overall are the rim diameter or rim width. Unless otherwise end cost as specified, the flap for the preferred rim is normally compared to supplied with the tire. (E.g. 200-20L or 20x7.50) tube-type tires Wheel and Valve Tire

52 MICHELIN® TRUCK TIRE SIZE Example: TUBE-TYPE TUBELESS 8.25R20 = 9R22.5 MARKINGS Nom. Cross Section 8.25 9 Most truck tire sizes are indicated by the section Remove .25 width in inches, followed by R for radial, followed Add 1 to 8 = 9 by the rim or wheel diameter in inches: Rim Diameter 20 Add 2.5 to Rim Diameter 20 + 2.5 = 22.5 TUBE-TYPE TUBELESS Thus we have 9R22.5 Tubeless. 10.00R20 11R22.5 10.00 = nominal section 11 = nominal section in inches in inches R=radial R = radial 20 = rim or wheel 22.5 = rim or wheel diameter in inches diameter in inches Tube- Tubeless Type Type 20" 22.5"

EQUIVALENT SIZES TUBE-TYPE TUBELESS TYPE 8.25R15 9R17.5 8.25R20 9R22.5 9.00R20 10R22.5

NOTE: A “rule-of-thumb” formula for finding 10.00R20 11R22.5 Section Eight TUBE TYPE TIRE equivalent tubeless sizes from tube-type: Take 11.00R20 12R22.5 nominal section width and remove all figures after 10.00R22 11R24.5 the decimal point. Add 1 to nominal section and 11.00R22 12R24.5 add 2.5 to rim diameter.

53 GENERAL INSTRUCTIONS FOR MOUNTING AND DEMOUNTING TUBE-TYPE TIRES

A tire cannot perform properly unless it is e. Always install new valve cores, and metal valve mounted properly on the correct size rim or wheel. caps containing plastic or rubber seals. For The following are general instructions for tires requiring ‘O’ Rings, be sure to properly demounting and mounting Michelin® tube-type install a new silicone ‘O’ Ring at every tire tires. For detailed instructions on mounting and change. demounting truck tires on particular types of rims and wheels, refer to the instructions of the rim and f. Always use a safety device such as an inflation wheel manufacturer or the RMA wall charts. cage or other restraining device that will con- strain all rim/wheel components during an Do not re-inflate any tires that have explosive separation of a multi-piece been run underinflated or flat without rim/wheel, or during the sudden release of the careful inspection for damage. If run- contained air of a single piece wheel that is in flat damage is detected, scrap the tire. compliance with OSHA standards. Never stand A tire is considered run-flat if it is over a tire or in front of a tire when inflating. Always use a clip-on valve chuck with an in-line found to be 80% below recommended valve with a pressure gauge or a presettable reg- operating pressure. This can result in ulator and a sufficient length of hose between serious injury or death. The tire may be the clip-on chuck and in-line valve (if one is damaged on the inside and can used) to allow the employee to stand outside explode while you are adding air. The TUBE TYPE TIRE the trajectory path when inflating. Section Eight rim parts may be worn, damaged or dislodged and can explosively separate 2. TIRE AND RIM LUBRICATION:

1. SELECTION OF PROPER COMPONENTS It is essential that an approved tire mounting AND MATERIALS: lubricant be used. Preferred materials for use as bead lubricants are vegetable oil soaps or animal a. All tires must be mounted with the proper soaps, in solution. Never use antifreeze, silicones, Michelin tube and flap (if required) and rim or or petroleum-base lubricants. Improper ratios of wheel as indicated in the specification tables. approved lubricants and water may have a harmful For complete tire specifications, refer to appli- effect on the tire and wheel. cation specific data books. (See Introduction for listing.) The lubricant serves the following three purposes: • Minimizes the possibility of damage to the tire b. Make certain that rim/wheel components are beads from the mounting tools. properly matched and of the correct dimen- • Eases the insertion of the tire onto the rim by sions for the tire. lubricating all contacting surfaces. c. Always fit a new Michelin® tube in a new mount- • Assists proper bead seating (tire/rim centering) ing. Since a tube will exhibit growth in size and helps to prevent eccentric mountings. through normal use, an old tube used in a new Apply a clean lubricant to all portions of the mounting increases the possibility of tube creas- tire bead area and the exposed portion of the flap ing and chafing, possibly resulting in failure. using sufficient but sparing quantities of lubricant. d. Always install a new flap in a new mounting. Also, lubricate the entire rim surface. Avoid using A flap, through extended use, becomes hard excessive amounts of lubricant, which can and brittle. After a limited time, it will develop a become trapped between the tire and tube and set to match the tire and rim in which it is fitted. can result in tube damage and rapid air loss. Therefore, it will not exactly match a new CAUTION: It is important that tire lubricant be tire/rim combination. clean and free of dirt, sand, metal shavings or other

54 hard particles. These particles may lodge between inants. The tire should be mounted and inflated the tube and the flap edges resulting in splits in the promptly before lubricant dries. tube. The following practice is recommended: 3. PREPARATION OF WHEELS, RIMS AND TIRES: a. Use a fresh supply of tire lubricant each day Never weld or apply heat to a rim or wheel on drawing from a clean supply and placing the which a tire is mounted. lubricant in a clean portable container. a. Always wear safety goggles or face shields when b. Provide a cover for the portable container buffing or grinding rims or wheels. and/or other means to prevent contamination of the lubricant when not in use. For lubricants b. Inspect wheel/rim assemblies for cracks, distor- in solution, we suggest the following method, tion, deformation of flanges, side rings, lock which has proven to be successful in minimizing rings, etc. Using a file and/or emery cloth, contamination and preventing excess lubricant smooth all burrs, welds, dents, etc. that are pre- from entering the tire casing: provide a special sent on the tire side of the rim. Inspect the con- cover for the portable container that has a fun- dition of bolt holes on the wheels. nel-like device attached. The small opening of c. Remove rust with a wire brush and apply a rust the funnel should be sized so that when a swab inhibiting paint. is inserted through the opening into the reserve of lubricant and then withdrawn, the swab is d. Remove any accumulation of rubber or grease compressed, removing excess lubricant. This that might be stuck to the tire, being careful allows the cover to be left in place providing not to damage it. Wipe the beads down with a added protection. A mesh false bottom in the dry rag. container is a further safeguard against contam-

TUBE-TYPE TIRE MOUNTING/DEMOUNTING Section Eight TUBE TYPE TIRE

Any inflated tire mounted on a rim DEMOUNTING TUBE-TYPE TIRES contains explosive energy. The use of damaged, mismatched or improperly 1. If a tire has been running underinflated or if any assembled tire/rim parts can cause damage to the tire or wheel is suspected, the the assembly to burst apart with valve core should be removed prior to removing explosive force. If you are struck by the tire/wheel assembly from the vehicle axle. an exploding tire, rim part or the air This is to prevent a possible accident. blast, you can be seriously injured or 2. Before unlocking any side ring or lock ring, killed. Do not attempt to dismount remove the valve core and allow the tire to the tire while the assembly is still deflate completely. installed on the vehicle. Use proper tools to demount or mount rim parts. 3. Remove all rim or wheel parts. Never use a steel hammer to seat rim parts- use only rubber, plastic, or brass-tipped mallets. Striking a MOUNTING OF TUBE-TYPE TIRES wheel/rim assembly with a hammer 1. Insert the proper size Michelin® tube into the of any type can damage the tire or tire and partially inflate (3 psi) to round out the wheel and endanger the installer. tube (with larger sizes it may be necessary to Use a steel duck billed hammer only use bead spreaders – see Page 56 for mounting as a wedge. Do not strike the head instructions). of a hammer with another hard-faced hammer- use a rim mallet. 2. Insert the valve through the flap valve hole.

55 (Make sure the reinforced patch that is directly excess lubricant does not run down into the tire. over the flap valve hole is facing outwards.) Then insert the remainder of the flap into the tire. 4. Insert the valve through the flap valve hole. (As mentioned, the flap reinforced valve area must 3. Check the flap wings to insure against folding. face outwards.) Insert the remainder of the flap This is easily accomplished by placing your into the tire. hand into one tire side, then the other, and then running your hand along the entire flap wing. 5. Close the beads.

4. Inflate the tube until the flap is secured against 6. Follow steps 4 through 7 of the “Mounting of the tire wall and the beads start to spread apart, Tube-Type Tires”. making sure not to exceed 3 psi.

5. Apply a proper tire lubricant to both beads and INFLATION OF TUBE-TYPE TIRES the exposed flap. Make sure that excess lubricant does not run down into the tire. 1. An air line with an extension (30" minimum), in-line gauge, and a clip-on valve chuck should 6. Place tire, tube and flap on the wheel or rim, be used for inflation. Remove valve core and taking care to center the valve in the slot. lay the assembly flat on the ground. Using an 7. Fit side ring and lock ring, insuring that they are approved restraining device, inflate partially to properly positioned, locked, and are correct for seat beads. While the tire is still in the restrain- the ‘fitment’. ing device, make sure all rim components are centered and locked properly. If not, the tire must be deflated, broken down, re-lubricated and re-inflated. Do not attempt to seat the lock TUBE TYPE TIRE

Section Eight MOUNTING OF TUBE-TYPE TIRES ring by means of a hammer. USING MANUAL SPREADERS: 2. Deflate the tire by removing the air line. This is 1. Follow steps 1 through 3 of the “Mounting of to allow the tube to relax thus eliminating any Tube-Type Tires”. However, before inserting wrinkles or uneven stretching that may have the flap into the tire, position two bead spread- occurred during primary inflation. ers in the following manner: 3. Install the valve core and, using a safety cage, a. Place the first at a 90° angle to the valve. or other approved restraining device meeting (Flap is positioned between the spreader and OSHA standards, re-inflate the tire to the pres- the tube.) sure shown on the sidewall in order to insure proper bead seating. Then adjust the tire to the b. Place the second directly opposite the first. proper operating pressure. Never stand over a c. Spread the beads and insert the flap. tire or in front of a tire when inflating. Always use a clip-on valve chuck with an in-line valve d. Close the beads, remove spreaders. with a pressure gauge or a presettable regulator and a sufficient length of hose between the clip- 2. Follow steps 4 through 7 of the “Mounting of on chuck and in-line valve (if one is used) to Tube-Type Tires”. allow the employee to stand outside the trajectory path when inflating. MOUNTING OF TUBE-TYPE TIRES 4. Re-inspect the assembly for proper positioning USING AUTOMATIC SPREADERS: of all components. 1. Spread the tire beads. 5. Check for leaks and install a suitable valve cap.

2. Inflate the tube to approximately 3 psi. 6. Do not re-inflate any tires that have been run underinflated or flat without careful inspec- 3. Insert the tube into the tire. Apply a proper tire tion for damage. If runflat damage is detected, lubricant to the inside and outside surfaces of scrap the tire. A tire is considered run-flat if it both beads and to that portion of the tube that is found to be 80% below recommended oper- appears between the beads. Make sure that ating pressure.

56 Section Nine APPENDIX

GENERAL INFORMATION

Units of Measurement Pressure Unit Conversion Table

Quantity S.I. Units Other Units kPa bar lb/in2* kg/cm2* 100 1.0 15 1.0 Length m 1 inch (") = 0.0254 m or 25.4 mm 150 1.5 22 1.5 (meter) 1 mile = 1609 m (1.609 km) 1 kilometer = 0.621 mile 200 2.0 29 2.0 250 2.5 36 2.5 Mass kg 1 pound (lb) = 0.4536 kg 300 3.0 44 3.1 (Kilogram) 1 kilogram (kg) = 2.205 lbs. 350 3.5 51 3.6 400 4.0 58 4.1 Pressure kPa 1 bar* = 100 kPa 450 4.5 65 4.6 (Pascal) 1 psi = 6.895 kPa 1 pound per square inch 500 5.0 73 5.1 1 kg/cm2 - 98.066 kPa 550 5.5 80 5.6 600 6.0 87 6.1 Speed m/s 1 kilometer per hour (kph)* = 650 6.5 94 6.6 (meter per 0.27778 m/s second) 1 mile per hour (mph) = 700 7.0 102 7.1 0.4470 m/s (or 1.60935 kph) 750 7.5 109 7.7

* Non S.I. unit to be retained for use in specialized fields. 800 8.0 116 8.2 850 8.5 123 8.7 Load Range/Ply Rating 900 9.0 131 9.2 B–4 F –12 L –20 950 9.5 138 9.7 C–6 G–14 M–22 1000 10.0 145 10.2 D–8 H –16 1050 10.5 152 10.7 E–10 J–18 * Values in psi and kg/cm2 rounded to the nearest practical unit.

Speed Symbol The ISO* SPEED SYMBOL indicates the speed at which the tire can carry a load corresponding to its Load Index under service conditions specified by the tire manufacturer.** APPENDIX Section Nine Speed Speed Speed Speed Speed Speed Symbol (kph) mph Symbol (kph) mph Symbol (kph) mph

A1 5 2.5 A7 35 22.5 F 80 50 A2 10 5 A8 40 25 G 90 56 A3 15 10 B 50 30 J 100 62 A4 20 12.5 C 60 35 K 110 68 A5 25 15 D 65 40 L 120 75 A6 30 20 E 70 43 M 130 81 N 140 87

* International Standardization Organization ** Exceeding the legal speed limit is neither recommended nor endorsed.

57 Approximate weight of materials Most materials and commodities vary in weight the following weights should be used only for approximation purposes. Exact weights should be obtained from local sources when making recommendations for truck or tractor-trailer equipment.

Lbs. per No. of Cu. Ft. Pounds Per: Beans, dry 60 Bushel Cement, Portland — 94 Bag Clay and Gravel, dry 100 2700 Cu. Yd. Clay and Gravel, wet 65 1755 Cu. Yd. Coal, Hard or Anthracite, broken 52-57 1400-1540 Cu. Yd. Coal, Soft or Bituminous, solid 79-84 2134-2270 Cu. Yd. Concrete 120-155 3200-4185 Cu. Yd. Corn, in ear — 70 Bushel Corn, shelled —- 56 Bushel Corn Syrup 86 11.5 Gallon Crude Oil 52 700 100 Gal. Fuel Oil 52-74 695-795 100 Gal. Gasoline 45 600 100 Gal. Gravel 100-120 2700-3240 Cu. Yd. Gravel and Sand, dry, loose 90-100 2430-2862 Cu. Yd. Gravel and Sand, dry, packed 110 2970 Cu. Yd. Gravel and Sand, wet 120 3240 Cu. Yd. Milk —- 845-865 100 Gal. Paper, average weight 58 Oats —- 32 Bushel Potatoes, White or Irish — 60 Bushel Petroleum — 800 100 Gal. Sand, dry, loose 90-106 2430-2860 Cu. Yd. Sand, moist, loose 120 3240 Cu. Yd. Section Nine

APPENDIX Soy Beans —- 60 Bushel Water 62.4 835 100 Gal. Wheat —- 60 Bushel

58 Load Index The ISO LOAD INDEX is a numerical code associated with the maximum load a tire can carry at the speed indicated by its SPEED* SYMBOL under service conditions specified by the tire manufacturer. (1 kg = 2.205 lbs.)

Load Load Load Index kg lbs. Index kg lbs. Index kg lbs.

100 800 1,765 134 2,120 4,675 168 5,600 12,300 101 825 1,820 135 2,180 4,805 169 5,800 12,800 102 850 1,875 136 2,240 4,940 170 6,000 13,200 103 875 1,930 137 2,300 5,070 171 6,150 13,600 104 900 1,985 138 2,360 5,205 172 6,300 13,900 105 925 2,040 139 2,430 5,355 173 6,500 14,300 106 950 2,095 140 2,500 5,510 174 6,700 14,800 107 975 2,150 141 2,575 5,675 175 6,900 15,200 108 1,000 2,205 142 2,650 5,840 176 7,100 15,700 109 1,030 2,270 143 2,725 6,005 177 7,300 16,100 110 1,060 2,335 144 2,800 6,175 178 7,500 16,500 111 1,090 2,405 145 2,900 6,395 179 7,750 17,100 112 1,120 2470 146 3,000 6,610 180 8,000 17,600 113 1,150 2,535 147 3,075 6,780 181 8,250 18,195 114 1,180 2,600 148 3,150 6,940 182 8,500 18,745 115 1,215 2,680 149 3,250 7,160 183 8,750 19,295 116 1,250 2,755 150 3,350 7,390 184 9,000 19,845 117 1,285 2,835 151 3,450 7,610 185 9,250 20,400 118 1,320 2,910 152 3,550 7,830 186 9,500 21,000 119 1,360 3,000 153 3,650 8,050 187 9,750 21,500 120 1,400 3,085 154 3,750 8,270 188 10,000 22,050 121 1,450 3,195 155 3,875 8,540 189 10,300 22,720 122 1,500 3,305 156 4,000 8,820 190 10,600 23,400 123 1,550 3,415 157 4,125 9,090 191 10,900 24,040 124 1,600 3,525 158 4,250 9,370 192 11,200 24,700 125 1,650 3,640 159 4,375 9,650 193 11,500 25,360 126 1,700 3,750 160 4,500 9,920 194 11,800 26,020 127 1,750 3,860 161 4,625 10,200 195 12,150 26,800 APPENDIX 128 1,800 3,970 162 4,750 10,500 196 12,500 27,565 Section Nine 129 1,850 4,080 163 4,875 10,700 197 12,850 28,355 130 1,900 4,190 164 5,000 11,000 198 13,200 29,110 131 1,950 4,300 165 5,150 11,400 199 13,600 30,000 132 2,000 4,410 166 5,300 11,700 200 14,000 30,870 133 2,060 4,540 167 5,450 12,000 201 14,500 31,980

*Exceeding the legal speed limit is neither recommended or endorsed.

59 VEHICLE ALIGNMENT – FIELD METHOD ATTACC PLUS SYSTEM

SET-UP INSTRUCTION PROCEDURES both sides of the vehicle to insure the steer tires are straight ahead (tolerance is 1⁄32" or 1 mm side TOOLS: to side). Adjust the steering wheels as necessary to • Chalk Line (no chalk) • Metric Tape come within tolerance. Mark the steering wheel • 1 pair of Jack Stands • Toe-Scribe column with a crayon for future reference. • 2 Cans of White Spray Paint • Large Plastic Bags • Vehicle Jack (10 Tons) • Flashlight 3. Measure for steering axle offset from the frame • Line Level and Wheel Chocks • 1 T-45A Tire Iron rail to the tire rib on both sides.

Refer to Michelin Video, ATTACC Plus (MWV41200) 4. Steering Stops: insure they exist and measure for reference. length. Stops control the angle of the turn and may be a consideration if abnormal steer tire SURFACE: Inspection site should be fairly level, wear is present. use Line Level if necessary to determine slope. Rear of Vehicle: STEER/DRIVE TIRES: Note: Tread Design, DOT, Tread Depth, PSI, Tire Conditions and mileage, and 1. Measure for drive axle offset by measuring, at all normal pertinent vehicle information. each drive axle wheel position, from the inner wheel flange to the inside of the frame rail (tolerance: 3⁄16" or 5 mm side to side).

VEHICLE POSITIONING: 2. Check ride height by measuring the distance from the lower part of the frame rail to the bot- 1. Drive vehicle straight into inspection site, at tom of the air spring (bag) housing. least 3 full vehicle lengths, to ensure it’s straight into site. Driving into and backing out of the 3. Measure for tandem axle skew by measuring work area several times will insure the vehicle’s between the rim flanges. Kneel between the out- suspension components are properly relaxed to side of the tires and hook the metric tape at hub- achieve proper measurements. height on one and by using a swinging arc on the other, determine the shortest distance between 2. Allow vehicle to roll to a stop, shut-off the them. Take a similar measurement on the other engine and let up on the clutch. side of the vehicle (tolerance is 1⁄8" or 3 mm).

3. Let vehicle fully stop by transmission, no 4. Measure for drive axle thrust by using the string brakes. Section Nine from the front drive axle to the steer position. APPENDIX 4. Engage tractor parking brakes and take out of Attach the string to the drive tire at hub height, gear, place Wheel Chocks on the drive tires. bring it across the rear sidewall, move to the steering axle, bring the string in toward the front rim until it touches the drive tire's front sidewall and measure the distance between the string MEASUREMENTS: and disc face of the rim (just below the dust cap). Repeat this method on the other side. Record all measurements. With all data recorded, review measurement of Front of Vehicle: drive axle offset. Any significant drive axle offset, if found (3⁄16" or 5 mm), must be factored into 1. Measure steering axle skew from the front of the the readings of drive axle thrust as determined outside U-bolt to the zerk fitting (or bolt) on the above by adding or subtracting the offset from the front spring pin perch. appropriate side. 2. Measure for straight ahead steering from the inner Draw a picture of the steer and drive axle orien- wheel flange to edge of the leafspring or frame on tation using recorded axle skew measurements.

60 Drive axle skew tolerance is based on wheel part of the steer tires will make contact with the base. 19⁄32" or 15 mm < 150", 3⁄4" or 20 mm 150- ground. Gently shake the vehicle to settle the 200", 1" or 25 mm > 200". suspension system, confirm steer ahead and measure toe between the scribe lines, first rear, 5. Check front end components and toe by jacking then front, to determine relative toe. Do this up front end. Place the floor jack under the axle with the paint cans on the ground, centered on for support, use the T-45A iron to lift the tire the scribe line and measure the distance and feel for bearing play, and in the wheel hand between the lines on the left and right tire at the hole to check for kingpin play. Using the spray paint can height. Subtract front from rear: posi- paint, lightly spray the center of tire tread and, tive result indicates toe-in, negative is toe-out. with the toe scribe, scribe the tire. While slowly At this paint can height: total toe-in should be 1 rotating the tire, check for lateral and radial mm 1 mm. runout by observing the scribed line. Additionally, observe the relative relationship 6. If checking for camber, with wheels straight between the wheel flange and the GG ring on ahead, drop a plumb line off the front fender over the lower sidewall of the tire to determine prop- the tire assembly center and measure the dis- er mounting of the tire on the wheel. Repeat tance between the string and rim flange at the top this process on the other steer tire. Check for and bottom. Divide your difference by 10 to con- steer ahead by referencing the mark on the vert mm to degrees. Use the paint can to extend steering wheel column and lower the vehicle on out from the fender if necessary. Repeat the pro- the folded plastic bags. Plastic should be folded cedure on the other steer position. Consider any to just larger than the tire footprint so that no floor slope and matching air pressures.

ATTACC PLUS Worksheet

Front Tandem Axle Skew String to wheel for drive axle thrust Spring to Flange

Drive Axle Offset Steer Offset Grease Zerk Drive Axle Offset to U-Bolt APPENDIX Section Nine

Drive Axle Offset Grease Zerk to U-Bolt Drive Axle Offset Steer Offset

Spring to Flange String to wheel for drive axle thrust Front Tandem Axle Skew

61 CASING MANAGEMENT

TIRE MANAGEMENT Operational Changes: 1. Speed limit: The national limit has continual- The goal of every truck operator is to achieve ly increased in the past decade.* the lowest possible operating cost, taking advan- tage of the performance built into each high tech 2. GVW: With the Surface Transportation Michelin radial truck tire. Tire maintenance, to Assistance Act of 1983 , the weight limits went include proper air pressures, repairs, vehicle align- from 73,280 lbs. to 80,000 lbs. With setback ment, and retreading, are all keys to help ensure axles, you can realistically load to 80,000 lbs. maximized performance and extended casing life. 3. Greater Vehicle Utilization: More loaded Over the past 10 years, a number of operational miles mean productivity gains. and product changes have occurred that should be considered when establishing tire use patterns. All of these changes lead to the casing arriving The single most important point of any program is at the retread stage with a higher level of fatigue. “Know your customer”. To utilize these casings to their maximum, casing management should be employed in the selection Tire Changes of the retread. 1 . New Tires: Today’s wider treads and deeper tread depths provide more original tread miles. The tire arrives at the retreader with more time CASING MANAGEMENT TODAY in service, more miles, and exposure to road conditions. Highway fleets typically employ the casing management pattern below: 2. Retread Changes: Wider treads, new tread Position of designs, and new compounds have increased Tire First Position of First Subsequent retread mileages. Used On Retread Use Retread Use Vehicle Changes Steer Drive or Trailer Drive or Trailer

1. Longer Trailers: There has been a move from Drive Drive Drive or Trailer 40' to 48' and 53' trailers as standards in the contract and private carriage business. Trailer Trailer Trailer

2. Wider Trailers: Widths have increased from

Section Nine 96" to 102". The combination of longer and APPENDIX In terms of casing fatigue, the severity of use is wider trailers increases the frequency of the as follows: duals being curbed. • Drive Axle – most fatigue. New drive tires (lug 3. Setback Front Axles: Moving the steer axle type) often can accumulate twice as many miles back increases stress on steer tires and load effi- (or more) before retreading than new steer or ciency by allowing better load distribution. The trailer tires can. The same is true for drive axle result is higher average axle loads. lug type retreads. The tires also run hotter (deeper tread) and with more torque. 4. Electronic Engines: Better engine control and more efficient operation improve the ability of the vehicle to maintain higher cruise speeds.*

* Exceeding the legal speed limit is neither recommended nor endorsed.

62 •Steer Axle – moderate fatigue. Steer axle tires operate at higher average loads than drive or TREAD SELECTION MATRIX trailer tires (20 to 40% higher). However, they In view of the above, it would seem best to wear out sooner than drive tires and are moved adopt the casing management pattern below for to lighter axles in the retread stage. tires in highway service: • Trailer Axle – least fatigue. The trailer tire Position of starts life with a shallow (cooler) tread and is Tire First Position of First Subsequent usually retreaded with a shallow retread. Used On Retread Use Retread Use Annual miles are low. The trailer tire casing usually sees more curb abuse, neglect, and old Steer Drive or Trailer Trailer age problems. Drive Trailer Trailer Thus, the practice of retreading new drive axle tires back to the drive axle puts the most highly Trailer Drive or Trailer Trailer fatigued casing back onto the most highly stressed wheel position. RETREAD RECOMMENDATIONS: CASING MANAGEMENT FOR 1. Follow the retread manufacturer's recommendations. THE FUTURE 2. Use the preferred tread size. The following guidelines are recommended in sorting casings for their next tread life. Such a sort- 3. Buff to the correct crown radius. ing would allow the fleet and retreader to make better decisions regarding the handling and utiliza- 4. Use pilot skives to measure undertread. 2⁄32" to tion of casings recovered from 6 x 4, 4 x 2, and trail- 3⁄32" is all that should remain when buffing is er applications. Casings which are judged to be complete. more “highly fatigued” should be retreaded in one of two ways:

1 . A low rolling resistance/low heat retread rubber PREVIOUS SERVICE LIFE in rib and drive (consult your retread supplier). In light of all these conditions, guidelines and 2. A shallow retread (no more than 15⁄32"). recommendations, the purchaser of casings for retreading should proceed with caution. Use the These retreads will reduce the operating tem- tread selection matrix when previous service life is perature in the crown of the tire. unknown.

Determining which tires are “highly fatigued” requires a working knowledge of each fleet's individual operation. The following guidelines can be used: APPENDIX 1. Two or more repairs on the casing. Section Nine

2. Heavy side wall abrasion.

63 COLD CLIMATE PRESSURE CORRECTION DATA

Because the air pressure inside a tire will used to ensure that the operating pressure and decrease when the vehicle is taken from a warm deflection of tires are adequate at the outside ambi- environment to a cold one, some adjustments may ent temperature. be necessary when adjusting the tire pressures of a Using the load and pressure charts below, deter- vehicle to be operated in very cold temperatures. mine the appropriate “Recommended Pressure” These adjustments are only necessary if the required for the axle load. Then find the same pres- pressures are verified and adjusted inside a heated sure down the left column of the table to the right. garage with an air supply that is also at the higher Going across to the relevant outside ambient temper- room temperature. (No adjustment necessary if ature you will find the corrected inflation pressure to done outside.) be used. In extreme cases, the following table should be

For example: • A log truck in Alaska has a front axle loaded weight of 12,700 lbs.. • The truck is equipped with 11R24.5 XZY-2™ LRG. • The recommended pressure for this fitment is 100 psi. • The truck is parked overnight in a heated garage. • The outside high forecasted for today is -20ºF. • The tire pressures are checked and adjusted prior to leaving the heated garage. According the the chart below, the tires should be adjusted to: 122 psi.

Adjusted Inflation Pressure (psi) (when inflating indoors at 65°F [18°C])

Recommended Outside Ambient Temperature Pressure °F 50° 40° 30° 20° 10° 0° -10° -20° -30° -40° -50° (psi) °C 10° 4° -1° -7° -12° -18° -23° -29° -34° -40° -46° 75 78 80 81 83 86 88 90 92 95 98 100 80 83 85 87 89 91 93 96 98 101 104 107 85 88 90 92 94 97 99 102 104 107 110 113 90 93 95 98 100 102 105 108 110 113 116 119 Section Nine

APPENDIX 95 98 101 103 105 108 111 113 116 119 123 126 100 103 106 108 111 113 116 119 122 125 129 132 105 109 111 114 116 119 122 125 128 132 135 139 110 114 116 119 122 125 128 131 134 138 141 145 115 119 122 124 127 130 133 137 140 144 148 151 120 124 127 130 133 136 139 143 146 150 154 158 125 129 132 135 138 141 145 148 152 156 160 164 130 134 137 140 144 147 150 154 158 162 166 171 Do not exceed maximum pressure capacity of the wheel. Consult wheel manufacturer.

64 CONVERSION TABLE

Size: 275/80R22.5 Overall Diameter: 40.1 Inches (decimal) Inches (fraction) Millimeters Degrees 0.03125 1/32 0.8 0.04 0.06250 1/16 1.6 0.09 0.09375 3/32 2.4 0.13 0.12500 1/8 3.2 0.18 0.15625 5/32 4.0 0.22 0.18750 3/16 4.8 0.27 0.21875 7/32 5.6 0.31 0.25000 1/4 6.4 0.36 0.28125 9/32 7.1 0.40 0.31250 5/16 7.9 0.45 0.34375 11/32 8.7 0.49 0.37500 3/8 9.5 0.54 0.40625 13/32 10.3 0.58 0.43750 7/16 11.1 0.63 0.46875 15/32 11.9 0.67 0.50000 1/2 12.7 0.71

SIX CRITICAL FUNDAMENTALS THAT COST MONEY

Low Air Pressure 20% of treadlife, a $30.00 cost may be associated This is the number one (along with improper with this situation. alignment) tire maintenance issue in the industry. The goal is to maintain a recommended/fleet target Dual Mismatched Height pressure based on the application and vary no The best method of avoiding damage due to more than 10 psi. Outside of this range, casing having tires of unequal circumferences is to inspect fatigue and irregular wear could cost in a range of and match tires so that the average diameter on $15 to $30.00 on a $300.00 tire. one axle is within 1⁄4 inch of the other. Based on a loss of 5 to 20% of treadlife, a $30.00 cost may be Valve Caps associated with this situation. Slow air loss is the primary result of missing or faulty valve caps. Properly installed and maintained Overinflation valve caps function as a secondary air seal and Again, the goal is to maintain a recommended/ means to keep debris away from the valve core. fleet target pressure based on the application and

vary no more than 10 psi. Overinflated tires are APPENDIX

Always install a new metal valve cap containing a Section Nine rubber or plastic seal. Consider a flow-through type more likely to be damaged by impact breaks and system to improve your maintenance program. The accelerated wear costing from 7 to 15% of life. resulting annual expense from missing valve caps/air A cost factor in a range of $15 to $30.00 could be loss may result in $5 to $15.00 per occurrence. associated with overinflation.

Dual Mismatched Air Pressure Irregular Wear The goal is to maintain tires in dual with equal Proper air pressure maintenance and a total pressure and within the target range of 10 psi. vehicle alignment program can eliminate most Mismatched pressures can cause a permanent irregular wear. An occurrence of irregular wear, on irregular wear pattern to develop and within just average, is associated with a 12% loss of tread life, a matter of weeks can potentially be a cause of or $15 to $36.00. It is also not uncommon for irreg- early tire removal. The matched tire will also be ular wear to cause a loss of up to 50% of usable affected by this difference. Based on a loss of 5 to tread, resulting in a much higher cost.

65 DOT SIDEWALL MARKINGS

All new tires sold in the United States must have Standard for Retreading. Tires manufactured prior a DOT number cured into the lower sidewall. All to the year 2000 used 3 digits rather than 4, the first retreaded tires must also have an additional DOT two numbers indicating the week and the last one affixed to their sidewalls as well. It is recommend- indicating the year of production, followed by a ed that this marking be placed in the lower sidewall solid triangle to indicate the 1990’s. Examples (i. e., near the original DOT code. Certain states may B6 DO A83 x 2104) of these codes and markings are require labeling in addition to the Federal require- shown below. ments certifying compliance with the Industry

New Tire markings required by the Department of Transportation: DOT XX XX XXX 0100 Meets Manufacturer Tire Size Tire Type Date of Manufacture DOT 2-digit 2-digit Code (Week/Year) Standards Identification (Mold/Chamber (Optional) Identification Mark Identification Mark) Mark

Truck Tire Retread markings as required by the Department of Transportation: R XX XX XXX 0100 Indicates Manufacturer Tire Size Tire Type Date of Manufacture Retread 2-digit 2-digit Code (Week/Year) Identification (Mold/Chamber (Optional) Identification Mark Identification Mark) Mark

Additional State Requirements for Truck Tire Retread markings: R XX XX XXX 0100 RSF2 Indicates Manufacturer Tire Size Tire Type Date of Manufacture RS indicates Retread 2-digit 2-digit Code (Week/Year) retread was Identification (Mold/Chamber (Optional) Identification produced under Mark Identification Mark) Mark Industry Retread Standards; F2 indicates the tire is

Section Nine acceptable for APPENDIX steer axle use and has been retreaded twice.

66 face aroundthebolthole.Onlyonenutoneach with two-pieceflangenutswhichcontactthedisc built intothehub.Hubpilotedwheelsareused The wheelcenterholelocatestheonpilots on thehubatcenterholeorboreofwheel. Hub PilotedDiscWheels mation onfasteners. Hardware forDiscWheels North America.SeeTMCRP217A, are commonlyusedoncommercialvehiclesin working on.Threebasictypesofmountingsystems to knowwhattypeofmountingsystemyouwillbe ponents, loss oftorque,brokenstuds, cracked fasteners) are mixedwithstudpiloted wheelcom- and thatthewheelisfitted totheproperhubs. er componentsareusedfor eachtypeofmounting, correct matingparts.Itis importantthattheprop- interchanged. Eachmountingsystemrequiresits circle pattern.Therefore,theycouldmistakenlybe and studpilotedwheelsmayhavethesamebolt used. WARN Before servicinganytruckwheel,itisessential If hubpilotedwheelcomponents (hubs,wheels, It isimportanttonotethatsomehubpiloted ING: HUB ANDSTUDPILOTEDWHEELTYPES Correct Componentsmustbe , formoredetailedinfor- are designedtocenter Figure 1:HubPilotedDiscWheelSystem Attaching on therightsideofvehicle.(Figure2) vehicle andthosewithrighthandthreadsareused left handthreadsareusedonthesideof require innerandoutercapnuts.Fastenerswith centers thewheels.Studpiloteddualwheels action oftheballseatnutsinboltholes centered bythenutsonstuds.Theseating Stud PilotedDiscWheels of identifyingthem.(Figure1) holes withnoballseat,whichprovidesavisualway Hub pilotedwheelshavestraightthroughbolt vehicle. Allstudandnutthreadsarerighthand. stud isusedtofastensingleordualwheelsa outer wheel. ( Figure3) nut interferingwiththe result intheinnercap inner wheelandwill cap nuttofitintothe will notallowtheinner and studpilotedwheels these partsarenotdesignedtoworktogether. wheels andpossiblewheellosscanoccursince Figure 2:StudPilotedDiscWheelSystem Mixing hubpiloted Figure 3:Improper Mounting are designedtobe 67

Section Nine APPENDIX Ball set, stud are mixed, loss of clamp load, broken studs, piloted wheels should cracked wheels, or possible wheel loss can occur not be used with since these parts are not designed to work together flange nuts because (See Figures 5 and 6.). Refer to TMC RP 608a, Brake they have larger bolt Drums and Rotors, and TMC RP 217A, Attaching holes and do not Hardware for Disc Wheels. have sufficient area near the bolt hole to support the flange nut. Slippage may Figure 4: Improper Mounting occur. Also the center hole is too large to center the wheel. (Figure 4)

It is also important to note that the hardware for stud and aluminum wheels cannot be arbitrari- ly mixed. If stud and aluminum wheel hardware Figure 5: Correct Figure 6: Incorrect

DISC WHEEL INSTALLATION PROCEDURE— RECOMMENDED MOUNTING TORQUE FOR DISC WHEELS

Torque Level Mounting Type Nut Tread Ft-Lb (Oiled)

Hub-piloted with flange nut 11/16”–16 300-400 M20 x 1.5 280-330 M22 x 1.5 450-500

Ft-Lb (Dry)

Stud-piloted, double cap nut 3/4”–16 450-500

Section Nine Standard type (7/8” radius) 1-1/8”–16 450-500 APPENDIX

Stud-piloted, double cap nut 15/16”–12 750-900 Heavy duty type (1-3/16’ radius) 1-1/8”–16 750-900 1-5/16”–12 750-900

Notes: 1. If using specialty fasteners, consult the manufacturer for recommended torque levels.

2. Tightening wheel nuts to their specified torque is extremely important. Under-tightening, which results in loose wheels, can damage wheels, studs and hubs and can result in wheel loss. Over-tightening can damage studs, nuts and wheels and result in loose wheels as well.

3. Regardless of the torque method used, all torque wrenches, air wrenches and any other tools should be calibrated periodically to ensure the proper torque is applied.

Reprinted with permission from TMC RP 222A, User’s Guide to Wheels and Rims, published by the Technology & Maintenance Council (TMC) of the American Trucking Associations, 2200 Mill Road, Alexandria, VA 22314 (703) 838-1776 .

68 RPM CALCULATION

MEASURED RPM • Torque – The presence of driving and braking torque can affect the RPM. At Michelin, Revolutions Per Mile (RPM) are officially determined using the SAE Recommended • Type and Condition of Pavement – Practice J1025. The test tires are placed as singles Asphalt vs. concrete, wet vs. dry can create dif- on the drive axle of the test vehicle and loaded to ference in RPM. the maximum dual load rating of the tire and set to the corresponding pressure. The vehicle is then driven over a straight 2-mile section at 45 mph CALCULATED RPM while the number of revolutions are counted. (Since speed minimally affects the results for radial Michelin Equation: tires, other speeds are allowed.) Averaging four RPM = 20,168 / (O.D. - .8d) runs that are within 1% of each other then derives O.D. = Overall Diameter the RPM measurement. d=Correction for deflection Afterwards, the results are double-checked d=(O.D./2) - SLR using shorter distances that are more easily SLR = Static Loaded Radius obtained. In addition to these, the test tire is com- (Ref. Data Book) pared to a known baseline tire on a road wheel. This latter method is very accurate and very repeat- able when using a similar baseline tire with a Example: 275/80R22.5 XDA® ENERGY known RPM. New Tire The SAE procedure recognizes that within the O.D. = 40.5 test method itself there will be some variation. In SLR = 18.8 fact, there are other factors that cause variation on d=(40.5/2) - 18.8 RPMs among similar tires. Be aware that just d=1.45 because similar tires have the same overall diameter this does not necessarily mean that they will RPM = 20,168 / ((40.5 – (.8 x 1.45)) have the same RPM. The SAE procedure deter- = 20,168 / (40.5 – 1.16) mines the RPM to within ± 1.5%. = 20,168 / 39.34 RPM = 512.6 (Calculated) Vs Data Some factors, which cause variation among Book (Measured) RPM = 513 tires, are:

• Load and Pressure – A difference in Load/Pressure could alter the RPM measure- At 50% worn ment by as much as 1.5%. If pressure is con- O.D. = 40.1 stant, going from an empty vehicle to a fully

SLR = 18.6 APPENDIX loaded vehicle can change the RPM by 1 to d=(40.1/2) – 18.6 Section Nine 1.5%. d=1.45 • Treadwear – The RPM varies from a new tire RPM = 20,168 / ((40.1 – (.8 x 1.45)) to a fully worn tire. This can affect RPM by as RPM = 518 (Calculated) much as 3% from the rated RPM.

• Tread Geometry – The height and stiffness of the blocks and the shape of the tread pattern can affect RPM.

69 RUNOUT AND VIBRATION DIAGNOSIS

Rotating assembly runout can influence vehicle If value is moderate continue with procedures vibration and contribute to irregular tire wear. below. If this value is excessive, remove and deflate the tire, break it loose from the rim, lubri- Following these procedures for verifying the cate, rotate the tire 180 degrees, re-inflate and concentricity of the guide rib area as well as insur- recheck runout. ing that both radial and lateral runout measurements are the lowest possible will aid in reducing any tire/wheel/hub assembly contribution.

Radial Runout

Tools needed: Tire runout gauge (or dial indicator), air pressure gauge, tread depth gauge, feeler gauge, six inch metal rule, tire marking crayon, jack and jack stands.

The first step is to eliminate possible sources of the disturbance (operation conditions, alignment posture, driveline component balance and angles, frame and chassis concerns, fifth wheel placement, and possible excessive stacked tolerances). Find out as much as you can that may be related to the issue to aid in the initial diagnosis. Incorrect bead seating can occur on one or both Examine the assemblies for proper air pressure, bead seats. This usually results in a high radial and/or Section Nine

APPENDIX proper mounting, verify balance if balanced, lateral reading. General cause is improper mounting inspect for tire and or wheel/rim damage. Verify procedures or wheel/rim is at tolerance limits. It may torque and proper component assembly on tube require taking 3 radial readings to detect: outside type or multi piece assemblies. shoulder, center rib, and inside shoulder.

Jack up the front end of the vehicle so axle is unloaded and place jack stands for support. Inspect front end components, to include wheel bearing and king pin play, suspension and rear assemblies.

Use the tire runout gauge to check for both radial (top photo) and lateral runout (bottom photo) for the rotating assembly. Values over .060 inch will be a detectable cause of vibration in steer assemblies and on recreational vehicles. Current TMC assembly tolerances are .095 inches, radial and lateral (See Balance and Runout, page 24).

70 Note: The bead seating surface of the tire and wheel do not match up as shown in previous photo. This incorrect seating is the result mismount. The TMC specification is 2/32nds (.062 inch). If both wheel and tire are lubricated and initial air inflation is done with the tire flat, you should have 1/32nd or less variance around the tire.

Check for this mismount condition with the six inch ruler, measuring is 4 locations around an unladen assembly.

Check for hub to wheel clearance on hub piloted assemblies with the feeler gauge. If you determine that the measured high spot lines up with the feeler gauge gap, rotate the assembly so the gap is at the top, loosen the lug nuts, and allow gravity to center the wheel on the hub. Hand tighten the top Verification of radial (top photo) and lateral nut, then tighten all nuts in the proper sequence (bottom photo) wheel runout is another step to be and recheck for runout. considered. TMC tolerances are .070 inch on tubeless steel disc wheels and .030 inch on tubeless aluminum disc wheels. APPENDIX Section Nine

On cast spoke and demountable rim assemblies, loosen and properly retighten the rim clamp nuts to the proper torque. Recheck for runout.

71 TOE MEASUREMENT – FIELD METHOD

Tools required: Metric Tape, Jack Stand, Toe- a balance weight and second, look for wear on the Scribe, 2 Cans of White Spray Paint, 2 Heavy Plastic spring shackle assembly. This check is more diffi- Bags, Vehicle Jack (10 Ton), Flashlight, Wheel cult to make and there are various ways to inspect Chocks, Tire Iron. for this wear. Consult the part manufacture for the proper way to inspect. Refer to Michelin Video, ATTACC Plus (MWV41200) for reference. On a dry tire, with a can of spray paint, marker or chalk (dusting with any coating material suitable Install wheel chocks on the rear tires and jack up for marking a section of tread), "highlight" a sec- the right front tire and place jack stand under axle. tion of the tread area around the tire. With a sharp (Note: conduct the following procedures on the pointed scribe, mark a thin line in the "highlighted" right front tire position, then do the same on the area while rotating the tire. (Note: at this point left front tire position.) observe the amount of radial runout by referencing this line to the rotating tire. Any runout greater Rotate the front tire to inspect for proper brake than 3/32nd" should be further investigated for adjustment, brake drum grab, bearing noise, lateral improper tire bead seating, improper tire/wheel runout, and obvious dynamic tire imbalance. Also runout and/or improper wheel torque procedure look at the tire guide rib area in relation to the rim during installation.) flange. If a notable difference in the distance between both is spotted, pay close attention to the Next, lower the vehicle and drive it forward, radial runout when you scribe your circumferential stopping in gear (without braking), or lower the toe measuring line later in this procedure. vehicle onto a frictionless surface. (Note: Properly cleaned turn plates offer the best frictionless sur- Insert Tire Iron into the wheel assembly at the face. Reasonable success can be obtained using 6 o’clock position and place your other hand at clean and lubricated slide plates, or, by using a 3 to the 12 o’clock position. With a rocking type 4 mil plastic sheet folded over itself 3 to 4 times on motion try to move the tire assembly up with the a smooth shop floor.) Prior to measuring, you lower bar and out towards you with your left should "joust" the vehicle by standing on the step, hand. If play is felt it is probably the result of and with your body weight shake the unit. This will loose wheel bearings or worn king pin bushings. If further relax the front suspension giving you a cor- you observe the brake chamber moving, it can be rect toe reading. isolated to the king pin bushing. If it does not move, it is likely the wheel bearings. Once the steer tires are down, mark a point on the front and rear of the each tire using the paint

Section Nine With your hands placed at the 3 o’clock and at cans as a reference to measuring an equal height APPENDIX the 9 o’clock position on the tire, try to move the from the floor that is perpendicular to your scribe tire in a rapid "left turn – right turn" type of motion. line. Measure from side to side with a tape meas- Feel and listen for any play. Play in this area would ure or a fine lined toe gauge. The difference in indicate either loose or worn tie rod ends, steering measurement across the front versus the rear of the arms, drag link ends, or steering box play. Any play tire is your toe. If it is a larger difference in the in this area should be further inspected to insure it front it is toe out, if it is larger in the rear, it is toe in. is within the vehicle and/or part manufactures specifications. Recommended Toe setting is +1/16" (1.5mm)

Two additional parts that can cause tire wear need to be checked. First, see if the brake drum has

72 TIRE DAMAGE – EFFECT AND CAUSE

All scrap tire failures are cause and effect relat- point to changes needed to avoid future scrap fail- ed. In the majority of the situations, it is the effect ures of this nature. Surprisingly, the majority of that we first see when we look at the tire damage. tubeless commercial scrap conditions are found in However, tire condition “effects” may have many the following 6 damage categories: causes. Often a pattern can be found that may

EFFECT CAUSE

RUN FLAT • Crown / sidewall injury resulting in air loss Run flat is defined as any tire operating at less (nail hole/bolt/debris penetrating the liner) than 80% of the recommended air pressure for • Leaking valve, grommet or wheel/rim the load being carried • Improper repair or improper repair procedures (premature failure of repair) • Bead damage due to mount/dismount

AIR INFILTRATION • Nail (bolt, screw, etc.) or any object that penetrates Any damage which opens the inner liner and into the tire and through the inner liner allows air under pressure, to migrate within the • Improper repair or improper repair procedures steel and rubber products (premature failure of repair) • Radial liner split (due to impact) • Bead area or inner liner damage (result of poor mounting procedures) • Inner liner cut (shipping or mounting damage) • Inner liner burn (e.g. electrical discharge damage)

PINCH SHOCK • Impact with a curb, pothole, road debris, etc. Crown/sidewall impact compressing the tire • Severe impact with any blunt object until the internal rubber products hit

IMPACT DAMAGE • Impact with a sharp cutting object. (A rupture • With or without a rupture - zipper usually indicates a rather severe impact.) • Crown, shoulder, or sidewall

FATIGUE RELATED DAMAGE • Run flat tires (mainly dual positions) • With or without a rupture - zipper • Impacts to steel (not filled or repaired) • Any damage which will allow the casing • Improper repair or improper repair procedures to oxidize or the casing plies to weaken (premature failure of repair) APPENDIX

or break • This may be a final removal condition on an old Section Nine or well used tire

BEAD DAMAGES • Heavy brake heat generating operations Bead turning, cracking/splitting, unwrapping • Mechanical brake system out of specification • Incorrect wheel width • Excessive flex from overload/underinflation • Mounting/Dismounting (insufficient lubrication, improper tool use, aggravated by heat (beads become brittle)) • Operational (spread axles, any high lateral scrub operation)

73 SCRAP INSPECTION FORM

Fleet:______Date:______

MFR. DOT TREAD RETREAD INFO CONDITIONS SIZE TYPE MFR. PL WK YR DEPTH # WHO WK/YR EFFECT CAUSE COMMENT

275/80R22.5 XDA-HT MX B6 29 92 07/32 2 RRL 148 RF SP

275/80R22.5 XT-1 MX B6 4 98 05/32 0 IM SI

275/80R22.5 XT-1 MX B6 1 98 08/32 0 PS CD

275/80R22.5 XDN2 MX M5 35 95 07/32 1 RRL 18 ZP IR

275/80R22.5 XDHT MX B6 29 92 07/32 2 RRL 148 FF SW Section Nine APPENDIX

Tire Condition Index: Effect - Cause RF = Run Flat IM = Impact PS = Pinch Shock ZP = Circumferential Fatigue Rupture (Zipper) SP = Sidewall Penetration SI = Sidewall Separation/Damage Induced CD = Bead Damage From Curbing IR = Improper Nail Hole Repair

Reference: Code Key 21, TMC Vehicle Maintenance Reporting Standards 2000 (VMRS 2000)

74 INDEX

A G S Ackerman Principle ...... 29 GCW (Gross Combination Weight) . . . . 12 Safety Device/Cage...... 18, 39, 56 AIRSTOP Tube...... 52 Gear Ratio...... 15, 39 Scrap Inspection Form ...... 74 Alignment...... 27 GVW (Gross Vehicle Weight) ...... 12 Section Height ...... 6 Alignment Checks (Frequency) . . . . . 30 GAWR (Gross Axle Weight Rating) . . . . 12 Siping ...... 10 Alignment Equipment ...... 30 Speed Restrictions ...... 8 Alignment Targets (TMC Guidelines) . . 29 H Speed Symbol ...... 57 Ambient Temperature ...... 8 Hub Piloted Disc Wheel ...... 67 - 68 Spinning ...... 26 Application Specification Data Table ...... 7 Long Haul ...... 4 I Static and Low Speed Load ...... 9 Regional ...... 4 Inflation Pressure ...... 8, 21, 22, 64 Steer Axle Geometry ...... 27 On/Off Road ...... 4 Steer Axle Setback (Skew)...... 28 Urban ...... 5 L Storage ...... 25 Commercial Light Truck...... 5 Load Index ...... 59 Stud Piloted Disc Wheel ...... 67 - 68 Industrial...... 5 Load per Inch Width Law...... 23 Suspensions ...... 34 Special Application Tires ...... 5 Load Range/Ply Rating...... 57 Suspension Fault ...... 35 - 36 Small Earthmover Tires ...... 5 Loaded Radius ...... 6 Aspect Ratio ...... 6, 52 Loads Per Axle ...... 8 T Axle Parallelism and Tracking . 30 - 31 Low-Profile Truck Tire ...... 10 Tandem Axle Parallelism ...... 29 ATTACC Plus System ...... 60 - 61 Lubrication ...... 14, 54 Tandem Axles ...... 20 Thrust Angle...... 29 B M Tire Damage ...... 73 Balance ...... 24 Maintaining the Tire...... 21 - 26 Tire Deflection ...... 6 Bias-Ply (Cross Ply) ...... 52 Maintaining the Vehicle...... 27 - 34 Tire Inspection ...... 22 Bib Alignment System ...... 30 Mounting The Tire ...... 13 - 20 Tire Mixing ...... 20 Braking Systems and issues ...... 33 Tubeless ...... 13 - 18 Tire Size Marking ...... 10, 53 Buff Radius ...... 47 Tube-Type ...... 54 - 56 Tire Wear...... 32 - 33 Buff Width ...... 49 X One ...... 38 Toe Wear ...... 32 Camber Wear ...... 32 C N Free Rolling Wear ...... 32 Camber ...... 28 Nominal Wheel Diameter ...... 6 Cupping Wear ...... 32 Casing Management...... 62 - 63 Flat Spotting Wear...... 32 Caster ...... 28 O Diagonal Wear ...... 33 Central Tire Inflation System...... 22 Offset - Dual and Front Wheels. . . . 15 Toe ...... 27 Chains ...... 25 Overall Diameter/Width ...... 6 Toe-Out-On-Turns ...... 29 Clearances ...... 15 - 17 Overinflation ...... 22 Torque ...... 18, 68 Lateral Clearances ...... 15 Tread Depth Measurements ...... 23 Vertical Clearances...... 16 P Troubleshooting ...... 35 - 36 Longitudinal Clearances ...... 16 Pressure Coefficients ...... 9 Tube Code ...... 52 Front Wheel Clearances...... 17 Pressure Monitoring System ...... 22 Tubeless Tire ...... 13 -20, 37 - 40 Cold Climate Pressure ...... 64 Pressure Unit Conversion Table. . . . 57 Tube-Type Tire ...... 52 - 56 Conversion Table ...... 65 Puncture Repair ...... 44 - 46 Cost Analysis ...... 50 - 51 U Cost Per Mile (CPM) ...... 50 R Underinflation ...... 22 Critical Six Fundamentals...... 65 Recreational Vehicles...... 22 Undertread ...... 48 Regrooving ...... 10 Units of Measurement ...... 57 D Repairs ...... 41 - 43 Damages (Radial/Crown) ...... 42 Repair Limit ...... 42 - 43 V Disc Wheel Installation ...... 66 - 67 Retreading...... 47 - 49 Vehicle Alignment . . . . 27 - 31, 60 - 61 DOT Sidewall Markings ...... 66 Revolutions Per Mile ...... 6 Vibration Diagnosis...... 70 - 71 Dual Assembly ...... 19 Rims...... 6, 8 Dual Spacing/Measuring...... 19 - 20 Rim Width...... 15 W Dynamometers ...... 25 RPM Calculation ...... 69 Wear Bar...... 23 Rotation ...... 26 Weight Class ...... 11 - 12 E Runout...... 20, 24, 70 - 71 Equivalent Sizes ...... 10 X X One...... 37 - 40 F Fifth Wheel...... 34 Flap Code ...... 52 Free Radius ...... 6 Fuel Efficiency/Saving/Analysis . . 1, 51 INDEX Fuel Analysis ...... 51

77 Michelin® Truck Tire Service Manual

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