1997 Buick Skylark Owner's Manual - Page 276

When It's Time for New Tires I Rust or dirt on wheel, or on the parts to a which it is fastened, can makewheel 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 wherethe 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 orwire brush later, if you off. need to, to getall the rust or dirt (See Index.) "Changing a Flat Tire" in the 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. You need a new tire any of the following statements if 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. 0 The tire has a 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.