185/55R15 vs 205/45R16
Switching from 185/55R15 to 205/45R16 increases the overall diameter by 6.4 mm (1.1%). That is within the usual ±3% guideline.
| 185/55R15 | 205/45R16 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 185 mm | 205 mm | +20.0 |
| Sidewall height | 101.8 mm | 92.2 mm | -9.6 |
| Rim diameter | 381.0 mm | 406.4 mm | +25.4 |
| Overall diameter | 584.5 mm | 590.9 mm | +6.4 |
| Circumference | 1,836.3 mm | 1,856.4 mm | +20.1 |
| Revolutions | 545 per km | 539 per km | -6.0 |
Speedometer effect
With 205/45R16 fitted on a car calibrated for 185/55R15, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 50.5 km/h |
| 80 km/h | 80.9 km/h |
| 100 km/h | 101.1 km/h |
| 120 km/h | 121.3 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 205 mm tire has a manufacturer-specified rim width range.
185/55R15 dimensions · 205/45R16 dimensions · Open in calculator