185/55R15 vs 195/50R15
Switching from 185/55R15 to 195/50R15 decreases the overall diameter by 8.5 mm (1.5%). That is within the usual ±3% guideline.
| 185/55R15 | 195/50R15 | Difference (mm / revs) | |
|---|---|---|---|
| Section width | 185 mm | 195 mm | +10.0 |
| Sidewall height | 101.8 mm | 97.5 mm | -4.3 |
| Rim diameter | 381.0 mm | 381.0 mm | +0.0 |
| Overall diameter | 584.5 mm | 576.0 mm | -8.5 |
| Circumference | 1,836.3 mm | 1,809.6 mm | -26.7 |
| Revolutions | 545 per km | 553 per km | +8.0 |
Speedometer effect
With 195/50R15 fitted on a car calibrated for 185/55R15, the real speed when the speedometer shows:
| Speedometer shows | Actual speed |
|---|---|
| 50 km/h | 49.3 km/h |
| 80 km/h | 78.8 km/h |
| 100 km/h | 98.5 km/h |
| 120 km/h | 118.3 km/h |
Smaller tires make the speedometer read higher than the actual speed. 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 195 mm tire has a manufacturer-specified rim width range.
185/55R15 dimensions · 195/50R15 dimensions · Open in calculator