1995 Chevrolet S10 Pickup Owner's Manual - Page 261

Uniform Tire Quality Grading The followinginformation relates to the system developed by the United States National Highway Traffic Safety Administration which grades tires by treadwear, traction and temperature performance. (This applies only to vehicles sold in the United States.) Treadwear The treadwear grade a comparativerating based on the wear rate of the is tire when tested under controlled conditions on a specified government test course. For example, tire graded 150 would wear one and a half (1 112) a times aswell on the government course as a tire graded 100. The relative performance of tires depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate. Traction -A, ByC The traction grades, from highest to lowest are: A, B, and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. A tire marked C may have poor traction performance. Warning: The traction grade assigned to this tire is based on braking (straight-ahead) traction tests and does not include cornering (turning) traction. Temperature - A, 9, C The temperaturegrades are A (the highest), B, and C, representing the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the material of the tire to degenerate and reduce tire life, and excessive temperature can lead to sudden tire failure. The gradeC corresponds to a level of performance which all passenger car tires must meet underthe Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratorytest wheel than the minimum required by law. 6-44