1995 Chevrolet Blazer Owner's Manual - Page 285

Uniform Tire Quality Grading The following information relates to thesystem developed by the United States National Highway Traffic Safety Administration which grades tires by treadwear, traction and temperature performance. (This appliesonly to vehicles sold in the United States.) Treadwear The treadwear grade is acomparative rating based on wear rateof the the tire when tested under controlled conditions on a specified government test course. For example, a tire graded150 would wearone and a half (1 1/2) times as well onthe government course as a tire graded 100.The relative performance of tires depends upon the actual conditions their use, of however, and may depart significantly from the norm due to variations in driving habits, service practicesand differences in road characteristics and climate. Traction -A, B, C The traction grades, from highest tolowest are: A, B, and C . They represent the tire's ability to on wet pavement as measured under controlled stop conditions on specified government test surfacesof asphalt and concrete. A tire markedC may have poor tractionperformance. Warning: The traction grade assigned to thistire is basedon braking (straight-ahead) traction testsand does not include cornering (turning) traction. Temperature - A, B, C The temperature grades areA (the highest),B, and C , representing the tire's resistance to the generation heat and its ability to dissipate heat when of tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the materialof the tire to degenerate and reduce tire life, and excessivetemperature can lead to sudden tire failure. The grade C corresponds to a levelof performance which allpassenger car tires must meetunder the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than minimum required by the law. 6-45