1995 Buick Skylark Owner's Manual - Page 233

Treadwear The treadwear gradeis a comparative rating based on the wear rateof the tire when tested under controlled conditions on a specified government test course. For example, a tire graded 150 would wear one and a half (1 1/2) times as wellon.the government course as a tire graded 100. The relative performance of tires depends upon the actual conditions their use, however, and of may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristicsand climate. Temperature A, B, C The temperature grades are (the highest), B, and C, A representing the tire's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditionson 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 grade C corresponds to a level performance of which all passenger car tires must meet under the Federal Motor Vehicle Safety StandardNo. 109. Grades B and A represent higher levelsof performance on the laboratory test wheel than the minimum required by law., Warning: The temperature grade for this tire is established for a that is properly inflated and not tire overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure. These grades are molded the sidewallsof passenger on car tires. - I I Traction A, B, C The traction grades,from highest to lowest are:A, B, and C. They represent the tire's ability to stop wet on pavement as measured under controlled conditions on specified government test surfaces asphalt and of concrete. A tire marked C may have poor traction performance. Warning: The traction grade assigned to this tireis based on braking (straight-ahead) traction tests and does not include cornering (turning) traction. - 6-32