1998 GMC Safari Owner's Manual - Page 308

Buying New Tires To find out what kind and size of tires you need, look at the Certificatioflire label. The tires installed on your vehicle when it was new had 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 have tires that are designed to to give proper endurance, handling, speed rating, traction, ride and other things during normal service on your vehicle. If your tires have an all-season tread design, the TPC number will be followed an "MS" by (for mud and snow). 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. A CAUTION: Mixing tires could cause you to lose control while driving. If you mix tires of different sizes or types (radial andbias-belted tires),the vehicle may not handle properly,and you could havea crash. Using tires of different sizes may also cause damage toyour vehicle. Be sure touse the same size and type tires on all wheels. It's all rightto drive with your compact spare, though. It was developed for use on yourvehicle. If you use bias-ply tires on yourvehicle, the wheel rim flanges could develop cracks after many miles of driving. A tire and/orwheel could fail suddenly, causing a crash. Use only radial-ply tires with the wheels on your vehicle.