2009 Cadillac STS-V Owner's Manual - Page 400

Buying New Tires GM has developed and matched specific tires for your vehicle. The original equipment tires installed on your vehicle, when it was new, were designed to meet General Motors Tire Performance Criteria Specification (TPC Spec) system rating. If you need replacement tires, GM strongly recommends that you get tires with the same TPC Spec rating. This way, your vehicle will continue to have tires that are designed to give the same performance and vehicle safety, during normal use, as the original tires. GM's exclusive TPC Spec system considers over a dozen critical specifications that impact the overall performance of your vehicle, including brake system performance, ride and handling, traction control, and tire pressure monitoring performance. GM's TPC Spec number is molded onto the tire's sidewall near the tire size. If the tires have an all-season tread design, the TPC Spec number will be followed by an MS for mud and snow. See Tire Sidewall Labeling on page 5-56 for additional information. GM recommends replacing tires in sets of four. This is because uniform tread depth on all tires will help keep your vehicle performing most like it did when the tires were new. Replacing less than a full set of tires can affect the braking and handling performance of your vehicle. The optional 18-inch performance tires, size 255/45ZR18 99Y, used on some vehicles, meets the General Motors Tire Performance Criteria Specification (TPC Spec) rating but the TPC Spec code has not been molded onto the tire's sidewall. If your vehicle has these tires, and you need to replace them, you can still get these TPC Spec rated tires by asking your GM dealer. Your GM dealer can order these tires by part number. This way, your vehicle will continue to give the proper endurance, handling, traction, and ride as the original tires. Winter tires with the same speed rating as your original equipment tires may not be available for H, V, W, Y and ZR speed rated tires. If you choose snow tires with a lower speed rating, never exceed the tire's maximum speed capability. 5-74