1998 Pontiac Firebird Owner's Manual - Page 301

After the tires have been rotated, adjust front and the rear inflation pressures as shown on the Tire-Loading Information label. Make certain that wheel nuts all are properly tightened. See "Wheel Nut Torque" in the Index. When It's Time for New Tires One way to tell when it's time for new tires is to check the treadwear indicators, which will appear whenyour tires have only 1/16 inch (1.6 mm) or less of tread remaining. 1 A CAUTION: Rust or dirt a wheel,or on the parts to which on wheel nuts become loose it is fastened, can make after a time. Thewheel could comeoff and cause an accident. When you 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 a paper towel to do this; but be or sure to use a scraper or wire brush later, if you need to, to get therust or dirt off. (See all "Changing a Flat Tire" in Index.) the You need a new tireif any of the 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 fabric. enough to show cord or The tire hasa bump, bulge or split. The tire has a puncture, cut or other damage that can't be repaired well because the size or location of of the damage. 0 6-48