1993 Buick Riviera Owner's Manual - Page 251

(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 norm due to variations the in driving habits, service practices and differences in road characteristics and climate. of The grade C corresponds to a level performance whicrall passenger car tires must meet under the No. 109. Grades Federal Motor Vehicle Safety Standard B and A represent higher levels performance on the of laboratory test wheel than minimum required by law. the Traction A, B, C The traction grades, from highest to lowest are:B, A, and C . They represent the tire's ability stop on wet to pavement as measured under controlled conditions on specified government test surfaces asphalt and of C concrete. A tire marked may have poor traction performance. 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 gradesare A (the highest), B, and C , representing the tire's resistance to generation of the heat and its ability dissipate heat when tested under to controlled conditionson 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 to sudden tire failure. - Warning: The temperature gradefor this tireis established for a tire that is properly inflated and not overloaded. speed, Excessive underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure. Those grade are molded on sidewalls of passenger the car tires. b While the tires available as standard or optional equipment on General Motors vehicles may vary with respect to these grades, all such tires meet General Motors performance standards and have been approved for use on General Motors vehicles. All passenger type (P Metric) tires must conform Federal safety to requirements in addition to these grades. 249