DOT HS 811 060 December 2008 Commercial Medium Tire Debris Study Final Report This document is available to the public from the National Technical Information Service, Springfield, Virginia 22161 This publication is distributed by the U.S. Department of Transportation, National Highway Traffic Safety Administration, in the interest of information exchange. The opinions, findings and conclusions expressed in this publication are those of the author(s) and not necessarily those of the Department of Transportation or the National Highway Traffic Safety Administration. The United States Government assumes no liability for its content or use thereof. If trade or manufacturers’ names or products are mentioned, it is because they are considered essential to the object of the publication and should not be construed as an endorsement. The United States Government does not endorse products or manufacturers. 1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. DOT HS 811 060 4. Title and Subtitle 5. Report Date Commercial Medium Tire Debris Study December 2008 6. Performing Organization Code 7. Authors 8. Performing Organization Report No. Woodrooffe, J.F., Page, O., Blower, D., & Green, P.E. UMTRI-2008-34 9. Performing Organization Name and Address 10. Work Unit No. Virginia Polytechnic Institute and State University Collegiate Square 11. Contract or Grant No. 460 Turner Street, Suite 306 DTNH22-05-D-01019 Blacksburg, VA 24060 Task Order # 0012 12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered National Highway Traffic Safety Administration July 2006 – June 2008 Office of Applied Vehicle Safety Research 14. Sponsoring Agency Code NVS-322 1200 New Jersey Avenue SE. Washington, DC 20590 15. Supplementary Notes Contracting Officer’s Technical Representative (COTR): Stephanie Binder Task Order Manager: Alrik L. Svenson 16. Abstract Trucking fleets and owners of commercial vehicles utilize both new and retread tires on their vehicles in the United States. Retread tires are used primarily for the cost advantage they provide over a similar new tire. Despite the advantages that retreaded tires may bring, public perception is that retread tires are less safe than new tires as evidenced by the amount of tire debris frequently found on the sides of U.S. Interstate highways. During summer 2007, the University of Michigan Transportation Research Institute (UMTRI) under a subcontract from Virginia Tech Transportation Institute (VTTI) collected and studied truck tire debris and discarded tire casings from five sites in the United States. A random sample (totaling 1,496 items) of the tire debris/casings collected was analyzed to determine the probable cause of failure and its original equipment or retread status. This report presents the methodology and results from this investigation into the underlying causes of truck tire failures and gives an overview of the crash safety problem associated with heavy-truck tire failures. Also, background information on the manufacture of a truck tire, the truck tire retread industry, tire failure modes, industry stakeholder perspectives, an overview of other previous tire debris studies, conclusions, and recommendations for topics for further research are given. 17. Key Words 18. Distribution Statement Tire, Retread, Tire Debris, Truck Tires Unlimited 19. Security Classification (of this report) 20. Security Classification (of this page) 21. No. of Pages 22. Price Unclassified Unclassified 236 i ii TABLE OF CONTENTS 1 INTRODUCTION .................................................................................................................. 1 1.1 Background..................................................................................................................... 1 1.2 Study Objectives ............................................................................................................. 2 1.3 Project Scope and Approach........................................................................................... 2 2 THE ANATOMY OF A TIRE, TIRE MANUFACTURE, AND THE U.S. TIRE INDUSTRY .................................................................................................................................... 5 2.1 Introduction..................................................................................................................... 5 2.2 The Process of Tire Manufacture.................................................................................... 5 2.3 The Structure of a Tire.................................................................................................... 6 2.4 Tire Design – Bias- or Radial-Ply................................................................................... 8 2.5 The Retread Tire Process.............................................................................................. 10 2.5.1 Mold-Cure, Pre-Cure, and Ring-Tread Retread Processes................................... 14 2.6 Retread Costs and Benefits ........................................................................................... 19 2.7 Regrooving.................................................................................................................... 22 2.8 The U.S. Commercial (Medium- and Wide-Base) Truck Tire Industry....................... 22 2.8.1 Standard Industrial Code Classification ............................................................... 22 2.8.2 North American Industry Classification System .................................................. 22 2.8.3 Tire Original Equipment Manufacturers............................................................... 23 2.8.4 Retread Tire Manufacturers .................................................................................. 23 2.9 Tire Identification Numbers and Authorization............................................................ 26 2.10 Passenger-Car Tire Retread Standards ......................................................................... 27 2.11 Commercial (Medium- or Wide-Base) Retread Tire Standards ................................... 28 2.12 Tire Plant Identity Code and Authorization.................................................................. 28 2.13 New Equipment and Retread Tire Manufacturing Statistics ........................................ 29 2.14 Original Equipment Tire Sales Statistics...................................................................... 30 2.15 Retread Tire Manufacturer Production Statistics ......................................................... 31 2.16 Demand for Tires .......................................................................................................... 32 2.17 Radial Tire Production.................................................................................................. 32 2.18 Number of Employees .................................................................................................. 32 2.19 Summary ....................................................................................................................... 34 3 REVIEW OF TIRE DEBRIS STUDIES .............................................................................. 35 3.1 Introduction................................................................................................................... 35 3.2 Technology Maintenance Council Studies ................................................................... 35 3.2.1 Study Objective..................................................................................................... 35 3.2.2 Composition of Study Team ................................................................................. 35 3.2.3 Study Period.......................................................................................................... 35 3.2.4 Locations............................................................................................................... 35 3.2.5 Methods ................................................................................................................ 36 3.2.6 Results................................................................................................................... 36 3.2.7 General Observations............................................................................................ 41 3.3 Need for Standards for Recapped Tires........................................................................ 41 3.3.1 Study Objectives ................................................................................................... 42 3.3.2 Composition of Study Team ................................................................................. 42 iii 3.3.3 Study Period.......................................................................................................... 42 3.3.4 Locations............................................................................................................... 42 3.3.5 Methods ................................................................................................................ 42 3.3.6 Results................................................................................................................... 42 3.3.7 General Observations............................................................................................ 43 3.4 Survey of Tire Debris on Metropolitan Phoenix Highways ......................................... 44 3.4.1 Study Objectives ................................................................................................... 44 3.4.2