How this tire size calculator works
Sidewall height equals width × aspect ratio. Two sidewalls plus wheel diameter produce overall tire diameter; circumference is π × diameter.
How to use it
- Tire width. Enter the value in mm.
- Aspect ratio. Enter the value in %.
- Wheel diameter. Enter the value in in.
- Request the result. Select “Show my result.” No account or email is required.
What to do with the number
Actual mounted diameter varies slightly by tire model, rim width, load and wear. Use manufacturer revolutions-per-mile data when exact speedometer or gearing calculations matter.
Planning estimate
Use this result as a starting point, not a guarantee. Product specifications, site conditions, manufacturer guidance, local codes, taxes, labor, tolerances, and rounding can change the real requirement or cost.
