1997 Pontiac Grand Am Owner's Manual - Page 271

IA -CAUTION: When It's Time for New Tires One way totell when it's time for new tires is to check the treadwear indicators, which will appear when your tires have only 1/16 inch (1.6 mm) or less of tread remaining. Rust or dirt a wheel, or on the parts to on which it is fastened, can make wheel nuts become loose after a time. The wheel could comeoff and cause an accident. Whenyou change a wheel, remove any rust or dirt from places where the wheel attaches to the vehicle. In anemergency, you can use a cloth or a paper towel to do this; but be sure touse a scraper or wire brushlater, if you off. need to, to get all the rust or dirt (See "Changing a Flat Tire" in the Index.) YOU need a new tire if any of the following statements are true: You can see the indicators at three or more places around thetire. You can see cord or fabric showing through the tire's rubber. The tread or sidewall is cracked, cut or snagged deep enough to show cord or fabric. The tire has a bump, bulge or split. The tire has a puncture, cut or other damage that can't berepaired well because of the size or location of the damage. 0 0 6-44