How to Measure a Press On Tire

Press on tires have 3 measurements, tire outside diameter, tire width, and tire inside diameter or the size of the hub the tire fits on.  These measurements are expressed in the tire size; for example a 21 X 7 X 15 is 21 inches tall, 7 inches wide and has an inside diameter of 15 inches.

See Chart Below
        Tire outside diameter “1”
        Tire width                     “2”
        Tire inside diameter    “3”

If the tire has been worn out to the point you can not read the tire size a very good estimate can be made by establishing 4 things, make and model of the truck and the tire width (2) and tire inside diameter (3).

A word of caution, when measuring the inside diameter (3) measure from the inside of the band and not from where the rubber meets the band.