Tire Size Calculator
Plus-sizing safety check before you buy wheels.
Speedometer reads
2.98% error
- Old diameter
- 24.97"
- New diameter
- 25.72"
- Actual 60 mph shows as
- 58.3 mph
How the Tire Size Calculator works
The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:
Frequently Asked Questions
How does the Tire Size Calculator work?
Enter your numbers above and results update instantly using standard formulas, computed entirely on your device.
Is the Tire Size Calculator free to use?
Yes — completely free with no signup required, and it works on phones, tablets, and desktops.