Tire Size Calculator
A tire size code such as 225/60R16 gives the width, the sidewall ratio and the rim size. This turns those numbers into the overall diameter of the tire.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
The sidewall is the width times the aspect ratio. The overall diameter is the rim plus two sidewalls.
The rolling distance is the circumference of the tire, the distance it covers in one full turn. Tires flatten a little under load, so the true figure can differ slightly.
Worked example
A tire with a 8.86 in width, a 60% aspect ratio and a 16 in rim measures 26.6 in across, and covers 6.97 ft in one turn.
Questions
Where do the numbers come from?
They are printed on the tire sidewall as width, aspect ratio and rim size.
Why does the diameter matter?
A different overall diameter changes speedometer readings and the car's gearing, so it is the number to check.
Can I compare two sizes?
Yes. Run the calculator for each size and compare the diameters or rolling distances.
More like this
- Mileage CalculatorMiles per gallon and mileage reimbursement.
- Drive Time CalculatorTrip time from distance, speed and breaks.
- RV Loan CalculatorMonthly payment on an RV loan.
- Flight Time CalculatorEstimated flight time from distance.
- Car Sales Tax CalculatorSales tax on a vehicle after a trade-in.
- Motorcycle Loan CalculatorMonthly payment on a motorcycle loan.