185/65R15 vs 215/45R17
Switching from 185/65R15 to 215/45R17 increases the overall diameter by 3.8 mm (0.6%). That is within the usual ±3% guideline.
| 185/65R15 | 215/45R17 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 185 mm | 215 mm | +30.0 |
| Sidewall height | 120.2 mm | 96.8 mm | -23.4 |
| Rim diameter | 381.0 mm | 431.8 mm | +50.8 |
| Overall diameter | 621.5 mm | 625.3 mm | +3.8 |
| Circumference | 1,952.5 mm | 1,964.4 mm | +11.9 |
| Revolutions | 512 per km | 509 per km | -3.0 |
Speedometer effect
With 215/45R17 fitted on a car calibrated for 185/65R15, 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 215 mm tire has a manufacturer-specified rim width range.
185/65R15 dimensions · 215/45R17 dimensions · Open in calculator