175/65R15 vs 205/45R17
Switching from 175/65R15 to 205/45R17 increases the overall diameter by 7.8 mm (1.3%). That is within the usual ±3% guideline.
| 175/65R15 | 205/45R17 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 175 mm | 205 mm | +30.0 |
| Sidewall height | 113.8 mm | 92.2 mm | -21.6 |
| Rim diameter | 381.0 mm | 431.8 mm | +50.8 |
| Overall diameter | 608.5 mm | 616.3 mm | +7.8 |
| Circumference | 1,911.7 mm | 1,936.2 mm | +24.5 |
| Revolutions | 523 per km | 516 per km | -7.0 |
Speedometer effect
With 205/45R17 fitted on a car calibrated for 175/65R15, 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 | 121.5 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.
175/65R15 dimensions · 205/45R17 dimensions · Open in calculator