-1.72%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 215/55R17, fitting 225/50R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.3 km/h | 25 mph | 24 mph |
| 60 km/h | 59.0 km/h | 37 mph | 37 mph |
| 80 km/h | 78.6 km/h | 50 mph | 49 mph |
| 100 km/h | 98.3 km/h | 62 mph | 61 mph |
| 120 km/h | 117.9 km/h | 75 mph | 73 mph |
Full comparison
215/55R17
Overall diameter668.3 mm · 26.31 in
Section width215 mm · 8.46 in
Sidewall height118.3 mm · 4.66 in
Circumference2099.5 mm · 82.7 in
Revolutions per mile767
Revolutions per km476
225/50R17
Overall diameter656.8 mm · 25.86 in
Section width225 mm · 8.86 in
Sidewall height112.5 mm · 4.43 in
Circumference2063.4 mm · 81.2 in
Revolutions per mile780
Revolutions per km485
-1.72%Safe swap — speedometer error is minor
Original
Overall diameter668.3 mm · 26.31 in
Sidewall height118.3 mm
Circumference2,099.5 mm
Revolutions / mile766.5
New
Overall diameter656.8 mm · 25.86 in
Sidewall height112.5 mm
Circumference2,063.4 mm
Revolutions / mile779.9
Speedometer & odometer error
The new tire changes overall diameter by -1.72%. With a speedometer calibrated to the original tire, that same percentage is how far the speedometer and odometer read off — a taller tire means your true speed is higher than indicated and the odometer under-counts distance.
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.3 km/h | 25 mph | 24 mph |
| 60 km/h | 59 km/h | 37 mph | 37 mph |
| 80 km/h | 78.6 km/h | 50 mph | 49 mph |
| 100 km/h | 98.3 km/h | 62 mph | 61 mph |
| 120 km/h | 117.9 km/h | 75 mph | 73 mph |
See individual specs: 215/55R17 · 225/50R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.