1996 Oldsmobile 88 Owner's Manual - Page 271

When It's Time for New Tires One way to tell when it's time for new tiresis to check the treadwear indicators, which will appear when your tires have only 1/16 inch (1.6 mm) or less of tread remaining. Buying New Tires To find out what kind and size tires you need, look at of the Tire-Loading Information label. The tires installed on your vehicle when new had it was a Tire Performance Criteria Specification (TPC Spec) number on each tire's sidewall. When you get new tires get ones with that same TPC Spec number. That way your vehicle will continue to have tires that are desig to give proper endurance, handling, speed rating, traction, ride and other things during normal service o your vehicle.If your tires have an all-season tread design, the TPC number will be followed by "MS" an (for mud and snow). You need a new tire if any the following statements of are true: 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. 0 The tread or sidewall is cracked, cut or snagged deep enough to show cord fabric. or The tire has a bump, bulge or split. The tire has a puncture, cut or other damage that of can't be repaired well because the size or location of the damage. If you ever replace your tires with 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.