1994 Pontiac Bonneville Owner's Manual - Page 228

Uniform Tire Quality Grading The following information relatesto the system developed by the United States National Highway Traffic Safety Administration which grades tiresby treadwear, traction and temperature performance. (This applies onlyto vehicles sold in the United States.) 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 grade assigned to this tire is based on braking (straight-ahead) traction tests and does not include cornering (turning) traction. Warning: The temperature grade for this tire is established for a tire that is properly inflated and not overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tire failure. These grades are molded on the sidewalls of passenger car tires. While the tires availableas 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 to Federal safety requirements in addition to these grades. Temperature A, B, C The temperature grades are A (the highest), B, and C , representing the tire's resistance to the generation of 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 to sudden tire failure. The grade C corresponds to a level of performance which all passenger cartires must meet under the Federal Motor VehicleSafety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. - Treadwear The treadwear gradeis a comparative rating based on the wear rate the tire of when tested under controlled conditions on a specified government testcourse. For example, a tire graded 150 would wear one and a half (1 1/2) times as well onthe government course as a tire graded 100. The relative performanceof tires depends upon the actual conditionsof their use, however, and may depart significantly from the norm due to variations in driving habits, service practices and differencesin road characteristics and climate. Wheel Alignment and Tire Balance The wheels on your vehicle were aligned and balanced carefully at the factory to give you the longest tire life and best overall performance. Traction A, B, C The traction grades, from highest to lowest are: A, B, and C. They represent i the tire's ability to stop on wet pavement -