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. Add your email, then select “Email & show my result.”
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.