1993 Chevrolet Camaro Owner's Manual - Page 265

Treadwear The treadwear grade is a comparative rating based on the wear rate the tire of 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 well 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, B, C 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 no1 include cornering (turning) traction. Temperature - A, B, C The temperature grades are A (the highest), B, and C, representing the tire's resistance to the generationof 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 grade C corresponds to a level of performance which all passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A 261