+6.88%Not recommended — recalibrate the speedometer
Speedometer error
With a speedometer calibrated to 255/40R22, fitting 285/45R22 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 42.8 km/h | 25 mph | 27 mph |
| 60 km/h | 64.1 km/h | 37 mph | 40 mph |
| 80 km/h | 85.5 km/h | 50 mph | 53 mph |
| 100 km/h | 106.9 km/h | 62 mph | 66 mph |
| 120 km/h | 128.3 km/h | 75 mph | 80 mph |
Full comparison
255/40R22
Overall diameter762.8 mm · 30.03 in
Section width255 mm · 10.04 in
Sidewall height102.0 mm · 4.02 in
Circumference2396.4 mm · 94.3 in
Revolutions per mile672
Revolutions per km417
285/45R22
Overall diameter815.3 mm · 32.10 in
Section width285 mm · 11.22 in
Sidewall height128.3 mm · 5.05 in
Circumference2561.3 mm · 100.8 in
Revolutions per mile628
Revolutions per km390
+6.88%Not recommended — recalibrate the speedometer
Original
Overall diameter762.8 mm · 30.03 in
Sidewall height102 mm
Circumference2,396.4 mm
Revolutions / mile671.6
New
Overall diameter815.3 mm · 32.1 in
Sidewall height128.3 mm
Circumference2,561.3 mm
Revolutions / mile628.3
Speedometer & odometer error
The new tire changes overall diameter by +6.88%. With a speedometer calibrated to the original tire, that same percentage is how far the speedometer and odometer read off — a taller tire means your true speed is higher than indicated and the odometer under-counts distance.
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 42.8 km/h | 25 mph | 27 mph |
| 60 km/h | 64.1 km/h | 37 mph | 40 mph |
| 80 km/h | 85.5 km/h | 50 mph | 53 mph |
| 100 km/h | 106.9 km/h | 62 mph | 66 mph |
| 120 km/h | 128.3 km/h | 75 mph | 80 mph |
See individual specs: 255/40R22 · 285/45R22. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.