This speedometer error reference table shows the actual speed for a range of original tyre diameter values, assuming a new tyre diameter of 650 mm and an indicated speed of 100 km/h. Every figure is computed with the same engine that powers our Speedometer Error Calculator, so the numbers are exact.
| Original tyre diameter | Actual speed | Speedometer error |
|---|---|---|
| 160 mm | 406.25 | 306.25% |
| 320 mm | 203.13 | 103.13% |
| 470 mm | 138.30 | 38.30% |
| 630 mm | 103.17 | 3.17% |
| 950 mm | 68.42 | -31.58% |
| 1,300 mm | 50.00 | -50.00% |
| 1,900 mm | 34.21 | -65.79% |
| 3,200 mm | 20.31 | -79.69% |
| 4,400 mm | 14.77 | -85.23% |
| 6,300 mm | 10.32 | -89.68% |
How to use this table
Find the row closest to your original tyre diameter and read across to the actual speed. For a value between two rows, the real figure sits between them — or enter your exact numbers in the Speedometer Error Calculator for a precise answer.
Need a value that is not in the table? — the Speedometer Error Calculator does it instantly, for free, with the formula and a worked example built in.
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