1993 Cadillac DeVille Owner's Manual - Page 324

Treadwear The treadwear gradeis a comparative rating based on thewear rate of the tire when tested under controlled conditions on a specified government test course.For example, a tiregraded 150 would wear one graded and a half (1 112) times as well on the government course as a tire 100. The relative performance of tires dependsupon the actual conditions of their use, however, and may depart significantly from the norm due tovariations 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 pavement as measured under wet controlled conditions on specified government test surfaces of asphalt and concrete.A tire markedC may have poor tractionperformance. Warning: The traction grade assigned to this tire is based on braking (straight-ahead) traction tests and does not include cornering (turning) traction. - Temperature A, B, C The temperature grades are A (the highest), B, and C, representing the tire's resistance to thegeneration of 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 and excessive temperature can lead to life, The grade C corresponds to a level of performance sudden tire failure. which allpassenger car tiresmust meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on thelaboratory test wheel than the minimum required by law. Warning: The temperature grade for tire is established for a tire that this 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. Those gradesare molded on thesidewalls of passenger car tires. -