1995 Cadillac Seville Owner's Manual - Page 319

Uniform Tire Quality Grading The following information relatesto thesystem developed by the United States National Highway Traffic Safety Administration which grades tires by treadwear, traction and temperature performance. (This applies only to vehicles sold in the UnitedStates.) 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 tire graded 150 would wear one and ahalf (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 andclimate. 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 gradeassigned to this tire is based on braking (straight-ahead) traction tests and does not include cornering (turning) traction. Temperature - A, B, C The temperaturegrades are A (the highest), B, and C, representing the tire's resistance to the generation heat and its ability to dissipate heat of when testedundercontrolledconditions on a specified indoorlaboratory test wheel. Sustained high temperature can cause the materialof the tire to degenerate and reduce tirelife, 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 represent higher levels of performance on thelaboratory test wheel than theminimum required by law. 6-48