1995 Pontiac Bonneville Owner's Manual - Page 249

When it's Time New Tires for 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. The tire has a bump, bulge or split. The tire has a puncture, cut, or other damage that can't be repaired well because of the sizeor location of the damage. Buying New Tires To find out what kind andsize of tires you need, look at the Tire-Loading Information label. The tires installed on your vehicle when it was new had a Tire Performance Criteria Specification (TPC Spec) number on each tire'ssidewall. When you get new tires, get ones with that same TPC Spec number. That way, your vehicle willcontinue to have tires that are designed to give proper endurance, handling, speed rating, traction, ride and other thingsduring normal service on your vehicle. If your tires have anall-season tread design, the TPC number will be followed by an "MS" (for mud and snow). If you ever replace your tireswith those not having a TPC Spec number, make sure they are the same size, load range, speed rating and construction type (bias, bias-belted or radial) as your original tires. You need a new tire if 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. 6-36