1998 Chevrolet Blazer Owner's Manual - Page 316

Treadwear The treadwear grade isa comparative rating based on the wear rate of thetire when tested under controlled conditions on a specified government course. test For example, a tire graded would wear one and a 150 half (1 1/2) times as wellon the government course as a tire graded100. 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 practices and differences in road characteristics and climate. Temperature -- A, B, C Traction -- A, B, C The traction grades, from highest lowest, are A, B, to and C , and they represent the tire's ability stop on to 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 assignedto this tire is based on braking (straight ahead) traction tests and does not include cornering (turning) traction. The temperature grades are A (the highest),B, and C, representing the tire's resistance the generationof to heat and its ability dissipate heat when tested under to controlled conditions on specified indoor laboratory a test wheel. Sustained high temperature can cause the material of the tireto degenerate and reduce tire life, and excessive temperature can lead sudden tire to failure. The grade C corresponds to a level of performance which all passengercar tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levelsof performance on the laboratory test wheel than the minimum requiredby law. Warning: The temperature grade for tire is this established for a tire that properly inflated and not is overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible failure. tire 6-46