1993 Pontiac Firebird Owner's Manual - Page 255

Service & Appearance Care . Rust or dirt on a wneel, or on the parts to which it is fastenec can make wheel nuts become loose after a time. The wheel could come off 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 or a paper towel to do this; but be sure to ." use a scraper or wire brush later, you need io, to get all the rust or a 1 off. (See "Changing a Flat Tire" in the Index.) L 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 when your tires have only 2/32 inch (1.6 mm) or less of tread remaining. You need a new tire i f 0 You can see the indicators at three places around the tire. D 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. 11 0 0 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. ' ...254 Buying New Tires To find out what kind and size of tires you need, look at the Tire-Loading Information label. The tires installed on your vehicle when it was new had a Tire Performance Criteria Specification (TPC Spec) number on each tire's sidewall. When you get new tires, get ones with that same TPC Spec number. That way, your vehicle will continue to have tires that are designed to