HOW TO READ A TIRE SIDEWALL

Since tires play a major role in establishing the personality of a vehicle, many manufacturers require their tire suppliers to identify their Original Equipment (OE) tires with symbols or codes branded on the sidewalls.

The goal is to make it easier for owners to read a tire sidewall to identify and select exact replacements when the OE tires wear out. Matching the original tires exactly helps maintain the vehicle's integrity.

TIRE SIDEWALL MARKINGS

A. Tire Size

The tire size is a combination of letters and numbers used to define a particular tire's width, height, aspect ratio, construction type, and service description.

B. Department of Transportation (DOT)

The DOT code indicates that the tire is in compliance with U.S. Department of Transportation Motor Vehicle Safety Standards.

C. Tire Identification Number (TIN)

The letters and numbers following the DOT code make up the TIN. The TIN shows the manufacturer and plant code, tire size, and date the tire was manufactured. The TIN is molded onto both sides of the tire, although only one side may have the date of manufacture.

D. Tire Ply Material

The type of cord and number of plies in the sidewall and under the tread.

E. Uniform Tire Quality Grading (UTQG)

A tire information system that provides consumers with ratings for a tire's traction (from AA to C) and for temperature (from A to C). Tread wear is normally rated from 60 to 620. Ratings are determined by tire manufacturers using government-prescribed test procedures and are molded into the sidewall of the tire.

F. Maximum Cold Inflation Load Limit

This information tells the maximum load that can be carried and the maximum pressure needed to support that load. Find more information on tire pressure and inflation.

G. Tire Performance Criteria Specification (TPC Spec)

Most OE tires designed to GM's specific tire performance criteria have a TPC spec code molded onto the sidewall. GM's TPC specs meet or exceed all federal safety guidelines.