1997 Chevrolet Malibu Owner's Manual - Page 262

Treadwear The treadwear gradeis a comparative rating based on the wear rateof the tire when tested under controlled conditions on a specified government test course. For example, a tire graded would wear one and a half 150 (1 1/2) times as wellon the government course as a tire graded 100. The relative performanceof tires depends upon the actual conditions their use, however, and of may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate. Temperature -- A, B, C Traction -- A, B, C The temperature grades are (the highest),B, and C, A representing the tire's resistance the generation of to heat andits 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 life, and tire excessive temperature can lead to sudden tire failure. The grade C corresponds to a level performance of which all passengercar tires must meet under the Federal Motor Vehicle Safety Standard 109. Grades No. B and A represent higher levels performance onthe of laboratory test wheel than the minimum requiredlaw. by Warning: The temperature gradefor this tireis established for a tire that properly inflated and not is overloaded. Excessivespeed, underinflation, or excessive loading,either separately orin combination, can cause heat buildup and possible tire failure. The traction grades, from highest to lowest, are B, and A, C, and they represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces asphalt and concrete. of A tire marked C may have poor traction performance. Warning: The traction grade assigned to this tire based is on braking (straight ahead) traction tests and not does include cornering (turning) traction. 6-41