185/65R14 vs 215/40R17
Switching from 185/65R14 to 215/40R17 increases the overall diameter by 7.7 mm (1.3%). That is within the usual ±3% guideline.
| 185/65R14 | 215/40R17 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 185 mm | 215 mm | +30.0 |
| Sidewall height | 120.2 mm | 86.0 mm | -34.2 |
| Rim diameter | 355.6 mm | 431.8 mm | +76.2 |
| Overall diameter | 596.1 mm | 603.8 mm | +7.7 |
| Circumference | 1,872.7 mm | 1,896.9 mm | +24.2 |
| Revolutions | 534 per km | 527 per km | -7.0 |
Speedometer effect
With 215/40R17 fitted on a car calibrated for 185/65R14, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 50.6 km/h |
| 80 km/h | 81.0 km/h |
| 100 km/h | 101.3 km/h |
| 120 km/h | 121.6 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.
185/65R14 dimensions · 215/40R17 dimensions · Open in calculator