2004 Cadillac XLR Owner's Manual - Page 287

Buying New Tires To find out what kind and size of tires you need, look at the Tire and Loading Information label. For information about this label and where to find it, see Loading Your Vehicle on page 4-32. 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, GM recommends that you get tires 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, load range, traction, ride, tire pressure monitoring system 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). Whenever you 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. If you replace your vehicle's tires with those not having a TPC Spec number, the tire pressure monitoring system may give an inaccurate low-pressure warning. Non-TPC Spec tires may give a low-pressure warning that is higher or lower than the proper warning level you would get with TPC Spec numbered tires. {CAUTION: Mixing tires could cause you to lose control while driving. If you mix tires of different sizes or types (radial and bias-belted tires), the vehicle may not handle properly, and you could have a crash. Using tires of different sizes may also cause damage to your vehicle. Be sure to use the same size and type tires on all wheels. {CAUTION: If you use bias-ply tires on your vehicle, the wheel rim flanges could develop cracks after many miles of driving. A tire and/or wheel could fail suddenly, causing a crash. Use only radial-ply tires with the wheels on your vehicle. 5-63