205/65R15 vs 215/45R18
Switching from 205/65R15 to 215/45R18 increases the overall diameter by 3.2 mm (0.5%). That is within the usual ±3% guideline.
| 205/65R15 | 215/45R18 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 205 mm | 215 mm | +10.0 |
| Sidewall height | 133.2 mm | 96.8 mm | -36.4 |
| Rim diameter | 381.0 mm | 457.2 mm | +76.2 |
| Overall diameter | 647.5 mm | 650.7 mm | +3.2 |
| Circumference | 2,034.2 mm | 2,044.2 mm | +10.0 |
| Revolutions | 492 per km | 489 per km | -3.0 |
Speedometer effect
With 215/45R18 fitted on a car calibrated for 205/65R15, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 50.2 km/h |
| 80 km/h | 80.4 km/h |
| 100 km/h | 100.5 km/h |
| 120 km/h | 120.6 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.
205/65R15 dimensions · 215/45R18 dimensions · Open in calculator