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Q: What do the sidewall markings on my tire mean? – Mr. Brennan

A: Mr. Brennan,

The side wall markings on a tire provide descriptive information about the tire’s design. The following refers to the tire illustration below with the sidewall marking of 225/50R16:

225 – This number specifies the width in millimeters (i.e. 225 millimeters)

50 – This number is the Aspect Ratio, the ratio of sidewall height to width

R – Radial

16 – This number designates the tire’s diameter in inches (i.e. 16”)

92 – This number indicates the tire’s load-carrying capacity, known as the Load Index; as the number for the load index increases so does the load-carrying capacity. (All passenger car tires in the U.S. are also marked with their actual load limit in pounds.)

V – This letter denotes the Speed Rating, the maximum tire speed under controlled test conditions (“V” in this example is one of several types of speed ratings.)

PSI – Pounds per square inch. The maximum cold inflation rating for the tire.

DOT – Department of Transportation. This symbol indicates the tire meets or exceeds United States DOT safety standards; the letters and numbers following the DOT safety standards; the letters and numbers following the DOT symbol provide information about the tire manufacturer, tire size, and the date it was manufactured. 

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