1996 GMC Sonoma Owner's Manual - Page 269

After the tires have been rotated, adjust the front and rear inflation pressures as shown on the CertificationRire label. Make certain that all wheel nuts 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 when your tires have only 1/16 inch (1.6 mm) or less of tread remaining. Rust or dirt on wheel, or on the parts which a to it is fastened, 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 thevehicle. 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,if you need to, to get all the rust or dirt (See off. "Changing a Flat Tire" in the Index.) J You need a new tire if any of the followin g statements are true: 0 You can see the indicators at three or more places around the tire. You can see cord or fhbric 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. 6-47