For 1990-2009 cars

GM vehicles use P-metric tires. Most P-metric tire sizes do not correspond exactly to alpha-numeric tire sizes. Because of the difference, replacement tires should have the same TPC specification number as the original tires. If replacing P-metric tires with other sizes, consult a tire dealer. Tire companies are able to recommend the closest match of alpha-numeric to P-metric sizes within their own tire lines.

For tire inflation specifications, see the tire placard on the vehicle, or refer to Tire Inflation Pressure Specifications in Maintenance and Lubrication.