2001 GMC Sierra 1500 Pickup Owner's Manual - Page 398

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. Some commercial truck tires may not have treadwear indicators. Dual Tire Operation When the vehicle is new, or whenever a wheel, wheel bolt or wheel nut is replaced, check the wheel nut torque after 100, 1,000 and 6,000 miles (160, 1 600 and 10 000 km) of driving. For proper torque, see "Wheel Nut Torque" in the Index. The outer tire on a dual wheel setup generally wears faster than the inner tire. Your tires will wear more evenly and last longer if you rotate the tires periodically. If you're going to be doing a lot of driving on high-crown roads, you can reduce tire wear by adding 5 psi (35 kPa) to the tire pressure in the outer tires. Be sure to return to the recommended pressures when no longer driving under those conditions. See "Changing a Flat Tire" in the Index for more information. You need a new tire if any of the following statements are true: D You can see the indicators at three or more places around the tire. D You can see cord or fabric showing through the tire's rubber. D The tread or sidewall is cracked, cut or snagged deep enough to show cord or fabric. D The tire has a bump, bulge or split. D The tire has a puncture, cut or other damage that can't be repaired well because of the size or location of the damage. CAUTION: If you operate your vehicle with a tire that is badly underinflated, the tire can overheat. An overheated tire can lose air suddenly or catch fire. You or others could be injured. Be sure all tires (including the spare) are properly inflated. 6-56