1993 Oldsmobile Achieva Owner's Manual - Page 249

TEadwear The treadwear grade is a comparative rating based onthe wear rate of the tire when tested under controlled conditions on a specified government test course. For example, a tire graded 1 0 would 5 wear one anda half (1%)times as well on the governmentcourse as a tire graded 100. The relative performanceof tires depends uponthe actual conditions of their use, however, andmay depart significantly from the norm to due variations in driving habits, service practices and differences in road characteristics and climate. Traction-A, 4 C Temperature-A, B, C The traction grades, from highest to The temperature gradesare A (the lowest are: A, B, and C. They represent highest), B, and C, representing the the tire's ability to stop on wet pavementtire's resistance to the generation of heat as measured under controlled conditions and its ability to dissipate heat when on specified government test surfaces of tested under controlled conditions on a asphalt and concrete.A tire marked C specified indoor laboratory test wheel. may have poor traction performance. Sustained high temperaturecan cause Warning: The traction grade assigned the materialof the tire to degenerate and to this tire is based on braking (straight- reduce tire life, and excessive temperature can lead to sudden tire ahead) traction tests and does not failure. The grade C corresponds to a include cornering (turning) traction. level of performance whichal l passenger car tires must meet under the Federal Motor Vehicle Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. 247 I