Tire Size Calculator
Overall diameter equals rim diameter plus twice the sidewall height; sidewall height is width times aspect ratio.
This calculator is free to use. Enable JavaScript to enter your values and see a result instantly.
How it works
Overall diameter equals rim diameter plus twice the sidewall height; sidewall height is width times aspect ratio.
Worked example
A 225/55R17 tire has an outside diameter near 26.7 inches.
Keep in mind
Results are estimates; check the assumptions for your situation.