Example: Tire width: 225 mm · Aspect ratio: 45% · Wheel diameter: 17 in → Overall diameter: 25 in.
Circumference: 78.5 in
Revolutions per mile: 808
Sidewall height: 3.99 in
Frequently asked questions
How do I calculate tire size? Enter your numbers above and the result updates instantly. For example: Tire width: 225 mm · Aspect ratio: 45% · Wheel diameter: 17 in → Overall diameter: 25 in.
Is this Tire Size Calculator free? Yes — completely free with no sign-up or paywall. It runs entirely in your browser and keeps working offline; the numbers you enter never leave your device.
How accurate is it? It uses the standard published formula for tire size. Results are estimates for planning — not financial, tax, medical, engineering, or legal advice.