1997 GMC Sonoma Owner's Manual - Page 286

Buying New Tires To find out what kind and size of tires you neea, look at the CertificationRire 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 to have tires that are designed 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 by an "MS" (for mud and snow). If you ever replace your tires with those not having a P C Spec number, make sure theyare the same size, load range, speed rating and construction type (bias, bias-belted or radial) as your original tires. 1 A CAUTION: Mixing tires could cause you to lose control while driving. If you mix tires of different sizesor types (radial and bias-belted tires), the vehicle may not handle properly, and could have a crash. you Using tires of different sizes may also cause damage to your vehicle. Be sure touse the same size and type tires all wheels. on It's all right to drive with your compact spare (if you have one). It was developedfor use on your vehicle. 6-48