2003 GMC Sierra 1500 Pickup Owner's Manual - Page 448

Inflation -- Tire Pressure If your tires have too much air (overinflation), you can get the following: Unusual wear Badhandling 0 0 The CertificationDire label, which is on the rear edge of the driver's door, shows the correctinflation pressures for your tires when they're cold. "Cold" means your vehicle has been sitting for at least three hours or driven no more than 1 mile (1.6 km). Roughride Needless damage from road hazards Notice: Don't let anyone tell you that underinflation or overinflation is all right. not. If your tires It's don't have enough air (underinflation), you can get the following: Too much flexing 0 0 When to Check Check your tires once a month or more. Also, check the tire pressure of the spare tire. Too much heat Tireoverloading Bad wear Badhandling Bad fuel economy How to Check Use a good quality pocket-type gage to check tire pressure. You can't tell if your tires are properly inflated simply by looking at them. Radial tires may look properly inflated even when they're underinflated. Be sure to put the valve caps back on the valve stems. They help prevent leaks by keeping out dirt and moisture. 5-73