275/60R20 vs 285/45R22
Switching from 275/60R20 to 285/45R22 decreases the overall diameter by 22.7 mm (2.7%). That is within the usual ±3% guideline.
| 275/60R20 | 285/45R22 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 275 mm | 285 mm | +10.0 |
| Sidewall height | 165.0 mm | 128.2 mm | -36.8 |
| Rim diameter | 508.0 mm | 558.8 mm | +50.8 |
| Overall diameter | 838.0 mm | 815.3 mm | -22.7 |
| Circumference | 2,632.7 mm | 2,561.3 mm | -71.4 |
| Revolutions | 380 per km | 390 per km | +10.0 |
Speedometer effect
With 285/45R22 fitted on a car calibrated for 275/60R20, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 48.6 km/h |
| 80 km/h | 77.8 km/h |
| 100 km/h | 97.3 km/h |
| 120 km/h | 116.7 km/h |
Smaller tires make the speedometer read higher than the actual speed. 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.
275/60R20 dimensions · 285/45R22 dimensions · Open in calculator