Understanding Tire Markings

Original Equipment Approval Code

All tires must have a DOT, Department of Transportation numbers which indicate that the tire has passed all minimum DOT standards.

Uniform Tire Quality Grading (UTQG) Marking

The Department of Transportation requires each manufacturer to grade its tires under the Uniform Tire Quality Grade (UTQG) labeling system and establish ratings for treadwear, traction, and temperature resistance. These test are conducted independently by each manufacturer following government guidelines to assign values that represent a comparison between the tested tire and a control tire. While traction and temperature resistance ratings are specific performance levels, the treadwear ratings are assigned by manufacturers following field testing and are most accurate when comparing tires of the same brand.

Tire Size Markings

The tire size shown above is 225/50R16. The 225 represents its section width (tire width in mm). "50" is the tires "Aspect Ratio" (the ratio of the sidewall height to the tread width). The "R" represents tire construction, in this case radial, and the last item is the "16" which represents the rim/wheel size.

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