Go and take a look at your tire, and on the side tire wall, just above the rim, you will be able to see three numbers. The first will be a triple-digit, the second and third will be double digit. The first number is the Tire Width, the second number is the Tire Height Ratio (which gives the sidewall height as a percentage of total width, don’t ask why) and the third number is the diameter. All these measurements are in inches by the way and are everything you need to know in terms of tire size. For help with tire measurements, you may wish to check out our tire size calculator.