Speedometer Error
Calculate how much your speedometer deviates from true speed after changing tire size. Indicated vs actual speed table.
Tire A (current)
Tire B (new)
● Within safe range (±3%)
When your speedo reads 100 km/h, your true speed is
100.4 km/h
| Indicated (km/h) | True Speed (km/h) | Difference |
|---|---|---|
| 30 | 30.1 | +0.1 km/h |
| 50 | 50.2 | +0.2 km/h |
| 70 | 70.3 | +0.3 km/h |
| 90 | 90.3 | +0.3 km/h |
| 100 | 100.4 | +0.4 km/h |
| 110 | 110.4 | +0.4 km/h |
| 120 | 120.5 | +0.5 km/h |
| 130 | 130.5 | +0.5 km/h |
| 150 | 150.6 | +0.6 km/h |
| 180 | 180.7 | +0.7 km/h |
| 200 | 200.8 | +0.8 km/h |
Calculations use nominal dimensions; actual measurements can vary ±1–2% by manufacturer and model. Always follow your owner's manual and door-jamb placard.