2003 Chevrolet Express Van Owner's Manual - Page 304

Inflation -- Tire Pressure The Certificationrrire label, which is on the rear edge of the driver's door, shows the correct inflation 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). If your tires have too much air (overinflation), you can get the following: Unusual wear 0 Badhandling Roughride Needless damage from road hazards 0 0 Notice: Don't let anyone tell you that underinflation or overinflation is all right. It's not. If your tires don't have enough air (underinflation), you can get the following: Too much flexing Too much heat Tireoverloading 0 When to Check Check your tires once a month or more. Also, check the tire pressure of the spare tire. 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. Badwear Bad handling Bad fuel economy Be sure to put the valve caps back on the valve stems. They help prevent leaks by keeping out dirt and moisture. 5-61