1995 Pontiac Firebird Owner's Manual - Page 286

Uniform Tire Quality Grading The following information relates the system to 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 the United States.) in Warning: The traction grade assigned to this tire is based on braking (straight-ahead) traction tests does not and include cornering(turning) traction. Temperature A, B, C The temperature grades are A (the highest),B, and C, representing the tire's resistance to generation of the 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 tosudden tire failure. The grade C corresponds to a level performance of which a l passenger car tires must meet l under the Federal Motor Vehicle SafetyStandard No. 109. Grades €3 and A represent higher levels of performance on the laboratory test wheel than minimum required by law. the Warning: The temperature gradefor this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, underinflation,or excessive loading, either separately in combination, or can cause heat buildup and possible tire failure. These grades are molded on the sidewalls passenger of car tires. While the tires available standard or optional as equipment onGeneral Motors vehicles may vary with - Treadwear The treadwear grade is a comparative rating based on the wear rate of the tirewhen tested under controlled conditions on a specified government test course. For example, a tire graded would wearone and a half 150 (1 1/2) times as well on the government course as a tire of graded 100. The relative performance tires depends upon the actual conditions their use, however, and of may depart significantly from the norm to variations due in driving habits, service practices and differences in road characteristics and climate. Traction A, B,C The traction grades, from highest lowest are: A,B, to 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 markedC may have poor traction performance. - 6-53