How to Optimize your Tyre and Temperatures on your

Caravan/Camperinsert image here: and your150 x 80mm vehicle

www.kimberleygroup.com.au 20121126 2 Importance of Optimum Tyre and Temperature

Table of Contents

1. Why is tyre pressure and temperature so crucial?

2. What is the link between Tyre Pressure and Temperature?

3. Getting the starting pressure right

4. Adjusting the pressure with the 4PSI rule

5. Adjusting the pressure to the optimum

6. TPMS

7. Suggested Pressure and Speed for conditions

8. Conversion Table

9. Is there an Optimum Tyre Size?

10. Acceleration, Braking and Load Transfer

11. Specifications of TPMS

12. TPMS Kit from Kimberley

13. Tyre Markings/ Tyre Size

14. Tyre Ageing

kimberleygroup.com 3 Importance of Optimum Tyre Pressure and Temperature

This eBook addresses the question:

How much of Australia do you want to experience?

kimberleygroup.com 4 Importance of Optimum Tyre Pressure and Temperature Why is Tyre Pressure so crucial?

Your tyre’s inflation pressure is measured as pounds per square inch, (psi) or “Bar (metric). The maximum recommended psi for your tyres printed right on them.

However, manufacturers may print a lower recommended psi than your tyre can truly handle because the lower inflation rate will give you a softer ride.

If you over inflate your tyres, you might cause some safety hazards. You’ll definitely wear out the tyres more quickly. A tyre that is over inflated shows more wear along the center width of the tyre than along its edges. When your tyres develop uneven tread wear, it shortens the overall life expectancy of your tyre.

The proper inflation level on your tyres also affects how much load your car can carry. Every vehicle and camper trailer/ caravan comes with a tyre-load rating that tells you the maximum weight that your tyres can bear. However the tyre-load rating assumes properly inflated tyres. If you over inflate your tyres and overload the weight, you’re creating the perfect recipe for a tyre to blow out.

Over or Under-inflation contributes to: 1. Rapid and uneven tread wear 2. A loss in fuel economy, 3. Poor vehicle handling 4. Excessive heat buildup which may lead to tyre failure.

kimberleygroup.com 5 Importance of Optimum Tyre Pressure and Temperature What is the link between Tyre Pressure and Temperature?

Understanding how temperature affects and their pressure is important.

• pressure measures the amount of air in your tires at a given tempera- ture.

• Changes in the ambient air tempera- ture will affect your tire pressure. For every 5-degrees celius fluctuation in temperature, your tires gain or lose one PSI of pressure.

• Changes in the temperature from heat generated by the tyre caused by friction between your tires and the road will increase tire pressure.

• As the temperature of your tires rise, so will the pressure levels.

• This increase can cause overinflated tires to blow or underinflated tires to appear acceptable.

• This makes it important to consistently check your levels because in the morning after a near zero degrees overnight camp in the desert, your ambient temperature may rise from low single digits to high 30s or even in the 40s!

• This wild change in temperature in the outback makes it even more important to optimize your tyre pressures as you travel. Stay safe, have better performance & save repair downtime and money!

kimberleygroup.com 6 Importance of Optimum Tyre Pressure and Temperature

Getting the Starting Pressure Right

The Starting point for your Vehicle’s/ Camper Trailer/Caravan Tyre Pressure when cold is set by:

Every tyre has a maximum inflation pressure stamped on the side somewhere. This is the maximum pressure the tyre can safely achieve under load. It is not the pressure you should inflate them to.

There is a recommended pressure on the door pillar sticker.

You can use that as a “starting point” or you can use the “max. pressure-10%” theory.

According to a lot of travellers on many internet forums you can get the best performance by inflating them to 10% less than their recommended maximum pressure.

It’s a rule of thumb, and is just a starting point which we will refine from so dont be concerned if this appears to be “hear-say”.

From my experience it does seem to provide a better starting point for adjusting tyre pressures.

kimberleygroup.com 7 Importance of Optimum Tyre Pressure and Temperature

Adjusting the Pressure with “4PSI” rule of thumb

• After you inflate all tyres to either the pressure recommended by the manufacturer, or the maximum pressure-10%, tow your caravan for say a distance of 100 klm. We are assuming the ambient was cool and hence it is called a “cold tyre” reading.

• Upon stopping, immediately recheck your tyre pressure while the tyre is still warm.

• If your tyre pressure reading is greater than 4 psi from the “cold tyre” reading you took at the beginning of your trip, then the tyres are getting too hot and your starting tyre pressure was too low.

• Under inflated tyres wear unevenly and lead to increased fuel consumption. They can also impair the handling of the vehicle in the areas of braking and handling.

• If the tyre pressure reading is less than 4 psi from the “cold tyre” reading you took at the beginning of your trip, then your starting tyre pressure was too high.

• With off-road conditions, the guide could be “6PSI” instead of “4PSI”

• You will need to run the test again (once the tyre has completely cooled) with less pressure until you find the right balance.

kimberleygroup.com 8 Importance of Optimum Tyre Pressure and Temperature

Adjusting the Pressure to the Optimum!

You can adjust daiy the pressure for optimum conditions as the ambient temperature and road conditions change.

To check and set the optimum tyre pressure more accurately, you need to quickly develop your own chart of both pressure and temperature readings of the tyre “set”. This may be slightly different on the front and rear tyres and the off road camper trailer of caravan tyres. So you could end up with 3 sets of charts. You only need to do this once.

You make your own chart by recording pressure and temperature and charting this.

To do this you will need a TPMS (Tyre Pressure and Temperature Monitoring Systems). It will easily show you the readings and your “navigator” can record them as you drive. We will get to the optimum pressure in a further chapter... read on.

kimberleygroup.com 9 Importance of Optimum Tyre Pressure and Temperature TPMS (Tyre Pressure & Temperature Monitoring)

Is a screen based Tyre Pressure and Temperature Monitor a gimmick or another gadget for the driver?

Some wives would say “yes” and yet it couldn’t be further from the truth. So here is the short version for the non technical followed by the long version for the passionate traveller.

The main item Between you and the road are a set of Tyres. In fact when you turn the wheel to go around a corner, you turn the steel wheel and the tyre can try to “follow” your turn. If the tyre pressure is right, it will follow quickly, if not it may roll a little on the turn. If there is a little piece of recent tyre damage, this may open up on the turn creating a potential serious problem. The majority of serious road accidents in remote places that do not involve a second vehicle or animal are because of tyre failure.

What can make your types doubly vulnerable is if they become excessively hot. With excessive heat, the Tyres are at their limit or beyond their operating conditions.

A Tyre Pressure and Temperature Monitoring system does 2 things.

The first is the obvious: if there is a dropping pressure the system goes into alarm once the pressure changes below a set point.

The second is if the temperature rises above a set point. This is otherwise hard to measure and gives you an indication that the standard pressure you have set the Tyres at may not be optimum for the load, speed and ambient temperature. By adjusting your standard tyre pressure you can get optimum tyre wear without compromise to performance.

Safety first, economy second.

kimberleygroup.com 10 Importance of Optimum Tyre Pressure and Temperature TPMS (Tyre Pressure & Temperature Monitoring)

Remember that the energy and forces at work with a vehicle and its trailer is proportional to the square of the vehicles speed. As you double your vehicles speed from say 40km/h to 80 km/h, the poten- tial energy in both the vehicle and the trailer moving around goes up FOUR (4) times.

When approaching corrugations and difficult changes in road/track terrain, always reduce your speed. After sitting behind the wheel for several hours/day and several days, this is a difficult discipline to adhere to. Our guidelines are:

You need 3 sets of tyre pressures to get the best out of both your tyres and camper trailer /off road caravan:

1. Higher pressures for vehicle stability at higher speeds; 2. Lower pressures to reduce ground pressure and gain greater in difficult ground. 3. Very low pressures for soft sand or thick mud

This is Why a TPMS System and getting to the Optimum Tyre Pres- sure is crucial.

The Tyre Pressures will change with: • The Speed you are travelling at, • The Load, • And the road conditions as indicated above.

The Only thing you can change easily with these 3 parameters is your road speed.

The TPMS will show you how your tyre pressures are changing with road conditions and speed.

kimberleygroup.com 11 Importance of Optimum Tyre Pressure and Temperature TPMS (Tyre Pressure & Temperature Monitoring)

• Travelling at high speed (100km/hr +) on black tarmac or well graded dirt roads requires good vehicle and trailer stability. The greater “energy” in either your vehicle or trailer at high speed puts lateral forces on the wheels and therefore tyres in corner- ing and overtaking manoeuvres. In the end, the tyres take these forces. The lower the tyre pressure, the more the tyres will com- press and change shape under these forces. Therefore keep the tyre pressure high.

• Decreasing tyre pressure increases the tyre “footprint”. This reduces the pressure on the ground for better floatation. It also improves traction on difficult terrain.

• However, the lower tyre pressure for a given speed/load will increase the tyre wall temperature. The higher the tyre wall tem- perature makes the tyres more vulnerable to failure/punctures. The best variable to control here is SPEED. If you lower the maximum speed the tyre temperature rise should be acceptable.

• Tyre pressures should raise approx 5% for every 10 degrees Celsius increase in operating temperature. If there is a 20 degree increase from cold to hot, there will be a 10% increase in pres- sure. (5% is close to 1 psi in most cases)

• Do NOT exceed the maximum tyre pressure especially when the tyres are hot as published by the manufacturer and shown on the tyre.

• A good quality accurate tyre pressure gauge or a TPM System is essential– do not rely on those in the inflation hoses in petrol stations!

kimberleygroup.com 12 Importance of Optimum Tyre Pressure and Temperature Monitor your speed as well as pressure/ temperature

In this scenario:

• You are travelling on dirt/difficult roads

• You set the tyres pressures low.

• You start off restricting your speed but after a while, the road improves

• you want to increase your speed

• If you want to increase your speed, YOU MUST monitor your tyre pressures and temperatures. Depending on conditions you may have to increase your tyre pressures.

If you are using a TPMS, you can monitor and optimize this without having to get out and keep checking!

You can work to a 4PSI rule or 6 PSI rule depending on road conditions.

Over time you will establish with a TPMS the best Tyre Pres- sure/ temperature settings for your rig.

kimberleygroup.com 13 Importance of Optimum Tyre Pressure and Temperature Suggested Pressures and Speed for conditions

Gibber Hard Black Roads and Soft sand or Tyre Axle Load Road Tracks or thick mud “thin mud” Suggest Suggest Limit of Limit of Limit of 100k/hr 65k/hr 20k/hr 1800 kgs 3.4 bar 2.3 bar 1.2 bar Example Axle 900 kgs used is 49 psi 33 psi 17 psi BFG 265/75 Wheel/Tyre R16 1600 kgs 2.8 bar 1.9 bar 0.9 bar Axle 120Q Rat- 800 kgs 40 psi 27 psi 13 psi ing Wheel/Tyre 1400 kgs 2.4 bar 1.6 bar 0.7 bar 1400kgs Axle Max 700 kgs 35 psi 23 psi 10psi 160k/hr Max Wheel/Tyre 1200 kgs 1.9 bar 1.3 bar 0.6 bar Axle 600 kgs 27 psi 19 psi 9 psi Wheel/Tyre WARNING: This table is a guide. Local conditions, the load in your unit and the behaviour of your vehicle under different loads will change the way it handles. Control your speed at all times especially in difficult or un- known conditions These Pressures are for COLD – approx 15°C Temperatures For every 10°C temperature rise, increase desired temperature by 5% or approx 1psi.

kimberleygroup.com 14 Importance of Optimum Tyre Pressure and Temperature Conversion Table

Bar PSI Bar PSI 0.6 8.7 2.1 30.5 0.7 10.2 2.2 31.9 0.8 11.6 2.3 33.4 0.9 13.1 2.4 34.8 1 14.5 2.5 36.3 1.1 16.0 2.6 37.7 1.2 17.4 2.7 39.2 1.3 18.9 2.8 40.6 1.4 20.3 2.9 42.1 1.5 21.8 3 43.5 1.6 23.2 3.1 45.0 1.7 24.7 3.2 46.4 1.8 26.1 3.3 47.9 1.9 27.6 3.4 49.3 2 29.0 3.5 50.8

kimberleygroup.com 15 Importance of Optimum Tyre Pressure and Temperature Is there an optimum size tyre?

To minimise pressure increases, tyre engineers work on every one of the 200 ingredients that go into each high quality tyre.

The development of a tyre is consequently a very lengthy and com- plex process as it is matched to the application.

How wide should a Tyre be? Does wider provide better grip?

If the load is the same, the contact “patch” with the ground will be the same for a given tyre pressure regardless of the width of the tyre.

A wide tyre will therfore have a shorter “length of oval patch in con- tact with the ground” than a narrower tyre at the same pressure. In dry conditions this is good, but in wet conditions, a longer oval patch in the direction of travel may enhance road holding in wet conditions. (The is really a squashed oval rather than a rectangle)

The area of the contact patch does not affect the actual grip of the tyre. The things that do affect grip are the coefficient of friction and the load on the tyre - (tyre load sensitivity).

Rubber friction is broken into two primary components - adhesion and deformation or mechanical keying. Rubber has a natural adhe- sive property and high elasticity which allows it readily deform and fill the microscopic irregularities on the surface of any road. This has the effect of bonding to various surfaces, which aids in dry weather grip but is diminished in wet road conditions.

Changing the Tyre Pressure will therefore not significantly change the “grip” of the tyre in different conditions. It is the load on the tyre and the forces associated with speed.

kimberleygroup.com 16 Importance of Optimum Tyre Pressure and Temperature Acceleration, Braking and Load Transfer

During acceleration or braking grip is reduced partly from the change is suspension geometry and party from the transfer of load from one set of tires to another.

Since the coefficient of friction is changing (lower for higher loads), the net grip during acceleration is reduced.

In other words maximum grip occurs when all four tires are loaded equally.

In reality the contact patch is effectively spinning around your tyre at some horrendous speed. When you brake or corner, load-transfer happens and all the tyres start to behave differently to each other.

This is why weight transfer makes such a difference the handling dy- namics of the car. In braking for instance; weight moves forward, so load on the front tyres increases. The reverse happens to the rear at the same time, creating a car which can oversteer at the drop of a hat.

If the load-transfer shift because of a connected carvan or trail- er was suddenly unbalanced, a rapid left-right-left on the steering wheel would upset the load so much that the vehicle lost grip in the rear, went sideways, jack-knifed and rolled over.

There is a complete eBook on Towing Stability that has much more information on all the parameters that contribute to safe towing.

kimberleygroup.com 17 Importance of Optimum Tyre Pressure and Temperature Specifications of TPMS

1. SENSOR AND TRANSMITTER SPECIFICATIONS Battery life More than 7 years, nominal. Storage temperature -40oC to 125oC Operating temperature -30oC to 120oC Operating humidity 95% Operating frequency 433.92MHz Pressure monitoring range 0~87 psi Pressure reading accuracy At Normal condition ± 1psi at normal pressure range Temperature reading accuracy ± 4oC in normal environmental condition Transmission power Max 5 dBm Battery 3.0V Sensor weight 32g ±3g

2. RECEIVER SPECIFICATIONS Operating voltage 12V DC Operating current < 200mA Monitored temperature range -30oC to 105oC Operating temperature -30oC to 85oC

kimberleygroup.com 18 Importance of Optimum Tyre Pressure and Temperature TPMS Kits (Showing only 4 Sensors instead of 8 or 12 sensors depending on Kimberley Model)

kimberleygroup.com 19 Importance of Optimum Tyre Pressure and Temperature Tyre Markings/Tyre Sizes

If you take time to look at the side wall of your tyres, whether they be on your 4WD vehicle, caravan, camper trailer, you will find a great deal of import- ant information. Each tyre will have distinct markings. Light truck (L/T) tyres are often used on 4WD vehicles, caravans, Terms: ‘LT’ for light truck tyres. P = passenger car tyre ‘ST’ for Special Trailer tyre 205 = (width) is the metric mea- surement across the widest portion of the sidewall (section width) in millimeters. / = The slash is the mathe- matical term indicating ratio. 65 = (height of side wall) the mathematical result of divid- ing the section height (depth of the tyre cross-section from the tread to the bead) by the section width (see above). This may also be referred to as the profile or series of the tyre. Eg: low profile or 70 series tyre. Ratios approach- ing 1 are generally associated with high carrying capacity and lower speed while low ratio .70 to .35 generally are towards a high perfor- mance capability with high speed and handling quality. In this case, the tyre height is approx 75% of the tyre width.

kimberleygroup.com 20 Importance of Optimum Tyre Pressure and Temperature Tyre Markings/Tyre Sizes

R = an alphabetical term for a radial tyre. In a radial tyre the cords run perpendicular to the bead of the tyre directly across the crown to the opposite bead. 16 = (rim diameter) this numerical number is the diameter of the bead of the tyre in inches. Bead seat diameters are manufactured in ½ inch increments. This tyre is designed to fit a wheel with a 16 inch diameter. 95 V = load/speed index (see load range below). A speed designa- tion at which the tyre can carry the load corresponding to the Load Capacity Index. AT: All Terrain M = meets the Rubber Manufacturer’s Association standards for a mud tyre. These can also be recorded as combina- tions such as M/T for Mud Terrain.

Speed Symbol ‘LR’ is the load range and the ‘D’ is the defined car- Maxi- rying capacity. The higher the letter in the alphabet, mum Speed the higher the carrying capacity. The load range (km/ph) L 120 codes relates to the old system of plies. For exam- M 130 ple, ‘D’ is the 4th letter of the alphabet and multiply N 140 it by 2 (4 x 2 = 8) or 8 ply ‘rated’ tyre. (Another ex- P 150 ample is ‘E’ which is the 5th letter of the alphabet (5 Q 160 x 2 = 10) or 10 ply). This shows us that the more R 170 carrying capacity we need the higher load range we S 180 T 190 require. U 200 Load Range (LR) D = (8 ply rating) is the load carry- H 210 ing capacity of the tyre. (eg: D = Load Index 110, E V 240 = Load Index 116) Z 240 Max Load Single 1380 kg (3042 lbs) @ 450 kP3 (65 W 270 PSI) COLD Y 300 Max Load Dual 1260 kg (2778 lbs) @ 450 kP3 (65 PSI) COLD

kimberleygroup.com 21 Importance of Optimum Tyre Pressure and Temperature Tyre Markings/Tyre Sizes

Tyre Maximum Load Rating contd.

‘Max Load’ = the maximum load capacity of the tyre. Operating a tyre over its rated capacity may damage the tyre internally. ‘Single’ = is the stated capacity when the tyre is installed in a single tyre application ie: one tyre on each end of an axle. 3042 lbs = rated carrying capacity of the tyre in pounds when in- stalled in a single configuration. 65PSI = the minimum air pressure required to obtain the carrying capacity of 3042 lbs. If you reduce the inflation pressure the rated carrying capacity decreases. (Tyre pressure is measured in kilopas- cals (kPa) or pounds per squar inch (psi)). “COLD” = this is the inflation pressure of the tyre cold, that is the tyre temperature before you commence a journey. Tubeless = has no rubber tube. The tyre seals on the rim via the bead and it has an external valve Treadplies = rubber coated cords forming the ‘footprint’ of the tyre Polyester cord = a synthetic fibre that maintains strength properties at high heat levels and eliminates flat spotting. Tyre Load Rating Index Number Maxi- mum Permissible Load (kg) 60 250 70 335 80 450 90 600 100 800 110 1060 120 1400 130 1900

kimberleygroup.com 22 Importance of Optimum Tyre Pressure and Temperature Tyre Ageing

Even unused tyres perish over time especially those exposed to heat, sunshine (UV radiation) and salt spray. Tyres are marked with the production date of the tyre and understanding these marking can help you determine the age of a tyre. Spare tyres fitted to caravans, motorhomes, fifth wheelers and trail- ers are often exposed to the elements and can age prematurely. It is recommended that you do not use tyres more than 6 years old from the date of manufacture. If a tyre has been in use, it has been reported that the effect of ageing has been lessened to a degree, but depending on the wear they should be replaced before 10 years. If you are in any doubt about the age and wear of a tyre discuss it with a tyre expert or replace it. How do I tell the age of a tyre? Tyres carry a DOT (USA Dept of Transport) number on the sidewall that gives a production date. Since the year 2000 the numbers con- sist of 4 digits instead of 3. The first two digits indicate the calendar week of production and the next two the year of production. Eg: 3004 – the tyre was manufactured in the 30th week of 2004.

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How to Optimize your Tyre Pressures and Temperatures on your

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