2007 Pontiac Grand Prix Owner's Manual - Page 401
2007 Pontiac Grand Prix Manual
Page 401 highlights
Low-Profile Performance Tire (GXP) If your vehicle has P255/45R18 size tires on the front wheels and P225/50R18 size tires on the rear wheels, they are classified as low-profile performance tires. These tires are designed for very responsive driving on wet or dry pavement. You may also notice more road noise with low-profile performance tires and that they tend to wear faster. Notice: If your vehicle has low-profile tires, they are more susceptible to damage from road hazards or curb impact than standard profile tires. Tire and/or wheel assembly damage can occur when coming into contact with road hazards like, potholes, or sharp edged objects, or when sliding into a curb. Your GM warranty does not cover this type of damage. Keep tires set to the correct inflation pressure and, when possible avoid contact with curbs, potholes, and other road hazards. Tire Sidewall Labeling Useful information about a tire is molded into its sidewall. The examples below show a typical passenger vehicle tire and a compact spare tire sidewall. Passenger (P-Metric) Tire Example 401