Tire Size Calculator
Compare tire sizes, see diameter differences, and speedometer correction.
Diameter Difference
+10.9 mm
(+1.7%)
Speedometer at 60 mph
61.0 mph actual
| Metric | Original | New | Diff |
|---|---|---|---|
| Overall Diameter | 24.97" | 25.40" | 0.43" |
| Sidewall Height | 101.3 mm | 94.0 mm | -7.3 mm |
| Circumference | 78.5" | 79.8" | 1.3" |
| Revs/Mile | 808 | 794 | -14 |
| Revs/Km | 502 | 493 | -8 |
How It Works
Reading Tire Size: 225/45R17
- 225 — Tread width in millimeters.
- 45 — Aspect ratio (sidewall height = 45% of width).
- R17 — Radial tire with a 17-inch rim diameter.
When switching tire sizes, keep within 3% of the original diameter to maintain accuracy of your speedometer, odometer, and vehicle safety systems.
Tire Formulas
About the Tire Size Calculator
This tire size calculator provides quick everyday calculations for tips, discounts, passwords, and daily tasks. Compare tire sizes, speedometer correction, and revolutions per mile.
Use whenever you need a fast answer without opening a spreadsheet.
Adjust the inputs above to model your specific scenario with the Tire Size Calculator.
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