1995 Buick Roadmaster Owner's Manual - Page 253

Treadwear The treadwear gradeis a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test course. For example, atire graded 150 would wear one and a half (1 1/2) times as wellon the government courseas a tire graded 100. The relative performanceof tires depends upon the actual conditionsof their use, however, and may depart significantly from the n o m 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 to lowest are:A, B, and C. They represent the tire's ability stop on wet to pavement as measured under controlled conditionson specified government test surfaces asphalt and of concrete. A tire marked C may have poor traction performance. - The temperature grades are (the highest),B, and C, A representing the tire's resistance to the generation of heat andits 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, an 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 Standard 109. Grades No. B and A represent higher levels performance on the of laboratory test wheel than the minimum required by la Warning: The temperature gradefor this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, underinflation, or excessive loading,either separately or in combination, can cause heat buildup and possible tire failure. These grades are molded on the sidewalls of passenger car tires. Warning: The traction grade assigned to this is based tire on braking (straight-ahead) traction tests and does not include cornering (turning) traction. 6-37