1993 Pontiac Trans Sport Owner's Manual - Page 253

Service & Appearance Care Tmadwear Traction-A, B, C Temperature-A, B, C A The treadwear grade is a comparative The traction grades, from highest to The temperature grades are (the rating based on the wear rate the tire lowest are: A, B, and C.They represent highest), B, and C, representing the of of when tested under controlled conditions the tire's abilityto stop on wet pavement tire's resistance to the generation heat on a specified government test course. as measured under controlled conditions and its ability to dissipate heat when on specified government test surfaces tested under controlled conditions on a of For example, a tire graded1 0 would 5 specified indoor laboratory test wheel. wear one and a half times as well asphalt and concrete.A tire marked C (1%) Sustained high temperature can cause may have poor traction performance. on the government course as a tire the materialof the tire to degenerate and graded 100. The relative Performanceof Warning: The traction grade assigned reduce tire life, and excessive tires depends upon the actual conditions to this tire is based on braking (straighttemperature can lead to sudden tire of their use, however, and may depart ahead) traction tests does not and failure. The gradeC corresponds to a significantly from the norm to due include cornering (turning) traction. level of performance which all variations in driving habits, service passenger car tires must meet under the practices and differences in road Federal Motor Vehicle Safety Standard characteristics and climate. No. 109. Grades B and A represent higher levelsof performance on the laboratory test wheel than the minimum required by law. B B I 252