1997 Pontiac Grand Prix Owner's Manual - Page 319

After the tireshave been rotated, adjust the front and rear inflation pressures as shown on the Tire-Loading Information label.Make certain that allwheel nuts are properly tightened. See "Wheel Nut Torque" in the Index. When It's Time forNew Tires One way to tell 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. a Rust or dirt onwheel, o r on the parts to which it is fastened, can make wheel nuts becomeloose after a time. The wheel could come off and cause an accident. Whenyou change a wheel, remove any rust or dirt from places where the wheel attaches to the vehicle. In an emergency, you can use a cloth or a paper towel to do this;but be sure touse a scraper or wire brush later,you if need to, to get all the rust or dirt (See off. "Changing a Flat Tire" in the Index.) You need a new tire if any ofthe following statements are true: You can see the indicators at three or more places around the tire. 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 be repaired well because of the size or location of the damage. 0 0