175/70R14 vs 185/60R15
Switching from 175/70R14 to 185/60R15 increases the overall diameter by 2.4 mm (0.4%). That is within the usual ±3% guideline.
| 175/70R14 | 185/60R15 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 175 mm | 185 mm | +10.0 |
| Sidewall height | 122.5 mm | 111.0 mm | -11.5 |
| Rim diameter | 355.6 mm | 381.0 mm | +25.4 |
| Overall diameter | 600.6 mm | 603.0 mm | +2.4 |
| Circumference | 1,886.8 mm | 1,894.4 mm | +7.6 |
| Revolutions | 530 per km | 528 per km | -2.0 |
Speedometer effect
With 185/60R15 fitted on a car calibrated for 175/70R14, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 50.2 km/h |
| 80 km/h | 80.3 km/h |
| 100 km/h | 100.4 km/h |
| 120 km/h | 120.5 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 185 mm tire has a manufacturer-specified rim width range.
175/70R14 dimensions · 185/60R15 dimensions · Open in calculator