1997 Oldsmobile Achieva Owner's Manual - Page 275

Treadwear The treadwear grade is comparative rating based on a the wear rate of the tirewhen tested under controlled conditions on a specified government test course. For example, a tire graded 150 would wear one and a half (1 1/2) times as wellon 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 tovariations in driving habits, service practices and differences in road characteristics and climate. 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 temperaturecan lead tosudden tire failure. The gradeC corresponds to a level of performance which all passenger cartires must meet under the Federal Motor Vehicle Safety StandardNo. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. Warning: The temperature grade for this is tire 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. Traction -- A, B, C The traction grades, from highest to lowest, are A, B, and C, and they represent the tire's ability stop on wet to pavement as measured under controlled conditionson specified government test surfaces asphalt and concrete. of A tire markedC may have poor traction performance. Warning: The traction grade assigned tothis tire isbased on braking (straightahead)traction tests and does not include cornering (turning) traction. 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. Scheduled wheel alignment and wheel balancing are not needed. However, if you notice unusual tire wear or your vehicle pulling one way or the other, the alignment may need to be reset.If you notice your vehicle vibrating when driving on a smooth road, your wheels may need to be rebalanced. Temperature -- A, B, C The temperature grades are (the highest), B, and C, A representing the tire's resistance to the generation of heat and its ability to dissipateheat when tested under 6-45