Tire Size Calculator
Reads a metric tire size such as 225/45R17. Shows sidewall height, overall diameter in mm and inches, circumference, and revolutions per km and per mile.
Frequently asked questions
What do the three numbers mean?
In 225/45R17, 225 is the width in millimetres, 45 is the sidewall height as a percent of that width, and 17 is the rim diameter in inches.
Is this the exact size of my tire?
It is the nominal size. Real tires vary a little by brand, tread depth and inflation.
What about LT or flotation sizes like 33x12.50R15?
This tool reads metric sizes only. Flotation sizes already give the diameter in inches as the first number.