Tyre Circumference Calculator

How to use Tyre Circumference Calculator

1. Enter your figures in the units shown beside each field. Keep monetary inputs in the same currency; money results are currently displayed in USD.
2. Select the unit standard where the form offers a choice, then choose Calculate.
3. Read the breakdown and compare the worked example below. Change one assumption to see its effect.

Formula used

Sidewall = width × aspect ratio/100. Diameter in mm = rim inches × 25.4 + 2 × sidewall. Circumference = π × diameter.

Worked example

225/45R17 gives a 101.25 mm sidewall, 634.30 mm nominal diameter and 1,992.71 mm circumference.

What the result means

Nominal geometry does not establish safe fitment. Check approved sizes, load and speed ratings, wheel compatibility and clearance.

Check your result

Results retain calculation precision internally and round for display. Keep the input values with the result so you can reproduce it. Use Reset to restore the example inputs, or Copy result to copy the displayed answer.

If the result does not agree with your own calculation, report the page, inputs and expected answer. See our methodology and reference sources for the standards used.

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