275/55R20 vs 285/45R22
Switching from 275/55R20 to 285/45R22 increases the overall diameter by 4.8 mm (0.6%). That is within the usual ±3% guideline.
| 275/55R20 | 285/45R22 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 275 mm | 285 mm | +10.0 |
| Sidewall height | 151.2 mm | 128.2 mm | -23.0 |
| Rim diameter | 508.0 mm | 558.8 mm | +50.8 |
| Overall diameter | 810.5 mm | 815.3 mm | +4.8 |
| Circumference | 2,546.3 mm | 2,561.3 mm | +15.0 |
| Revolutions | 393 per km | 390 per km | -3.0 |
Speedometer effect
With 285/45R22 fitted on a car calibrated for 275/55R20, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 50.3 km/h |
| 80 km/h | 80.5 km/h |
| 100 km/h | 100.6 km/h |
| 120 km/h | 120.7 km/h |
Larger tires make the car go faster than the speedometer shows. Most speedometers also read slightly high from the factory.
Before you change size
- Check the sizes approved for your vehicle on the door-jamb placard or in the owner's manual.
- Check clearance to suspension, brakes and arches at full lock and full compression.
- Match or exceed the original load index and speed rating.
- Wider tires need an appropriate rim width; a 285 mm tire has a manufacturer-specified rim width range.
275/55R20 dimensions · 285/45R22 dimensions · Open in calculator