Travel & transport
Tyre size comparison
Compare nominal geometry and speed ratios for two metric radial sizes.
A clear answer. Here’s how.
Parses metric radial width/aspect/rim sizes, with optional P or LT prefix. Sidewall=width×aspect/100; diameter=rim inches×25.4+2×sidewall; circumference=π×diameter. Compares the nominal size and geometric speed ratio. Loaded radius, actual manufacturer dimensions, speedometer calibration, load/speed ratings, clearances and vehicle approval are not assessed.
See a worked example
Worked example
A fixed demonstration, separate from the values you enter above.
- Original size (e.g. 205/55R16)
- 205/55R16
- Comparison size
- 225/45R17
- Indicated speed (km/h)
- 100
Example result
| Nominal property | Original | Comparison |
|---|---|---|
| Section width (mm) | 205 | 225 |
| Sidewall height (mm) | 112.75 | 101.25 |
| Rim diameter (in) | 16 | 17 |
| Overall diameter (mm) | 631.9 | 634.3 |
| Circumference (mm) | 1,985.1723978 | 1,992.71222017 |
Geometric speed at 100 km/h indicated: 100.379806931 km/h. Actual calibration and fitment are not assessed.