scope:

Note: Nothing in the standard supersedes applicable laws and regulations.

Note: In the event of conflict between the English and domestic language, the English language shall take precedence.

Purpose.

Method A. To determine treadwear for various tire makes and designs on different road surfaces correlated to European market road systems.

Method B. Treadwear encompasses both uniform and non-uniform (irregular) treadwear characteristics. Uniform treadwear removes rubber from the tire at an equal rate across the entire tread surface. Uniform treadwear (unless excessive) does not create adverse issues for the vehicle. Irregular treadwear occurs when parts of the tread surface experience an accelerated treadwear rate compared to the neighboring portions of the tread surface. Irregular treadwear can create vehicle vibrations and excessive noise. This procedure describes the test requirements and test method for conducting the treadwear course (TPC-1) treadwear test. The procedure is used for all treadwear tests conducted on the Hercules TPC-1 treadwear schedule by prescribing the vehicle, suspension alignment, tires, wheels, and loading schedule for different vehicle types.

Method C. To evaluate treadwear performance, when driven on public roads. Method C describes the procedure, requirements and test methods to conduct an "Off Site Tire Wear - Durability Test". 1.2

Foreword - Method B. Summary of Method.

Treadwear properties, both uniform treadwear and irregular wear, are determined by operating the test system and a control system over a real-world treadwear schedule located in the Appalachian mountains near Cumberland, Maryland.

The vehicles are selected to represent the production intent system based on the vehicle suspension type, drive type, and weight distribution. The vehicles are validated from the standpoint of critical suspension design features. These critical suspension design features include the ride-toe properties, ride-camber characteristics, Ackerman error, and weight distribution.

It is suggested that the tires are mounted and balanced, screened on the low-speed uniformity equipment, match-mounted on the production intent wheels, dynamically balanced.

The 40 000 km (24 860 mi) treadwear test is divided into 64 shifts that are 625 km (388.5 mi), each shift consisting of a complete circuit of the treadwear course. The treadwear test includes three (3) ballast conditions for passenger cars and light trucks and four (4) ballast conditions for vans using passenger car tires. The tires are visually inspected after each shift and the groove/slot depths are measured at set distances into the schedule.

The vehicles are instrumented with a Treadwear Data Acquisition System to record vehicular accelerations during the treadwear test. The Treadwear Data Acquisition System consists of a Model 5 Level Detector, Model 2 Vehicle Speed Frequency Translator, calibrated speed display, power supply, and two (2) Schaevitz inclinometers.

Data and status reports are provided to General Motors (GM) at set distances during the schedules as indicated in Appendix E, Appendix F, or Appendix G as appropriate

Applicability.

Method A. For all tires.

Method B. This procedure is to be used as a final validation confirming the uniform and non-uniform treadwear characteristics of the tire/vehicle system on a customer-based schedule. The purpose is to identify adverse treadwear conditions as exhibited by the production intent system before they can be generated in the field on GM passenger cars, vans, and light trucks.