-0.95%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 215/55R16, fitting 205/50R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.6 km/h | 25 mph | 25 mph |
| 60 km/h | 59.4 km/h | 37 mph | 37 mph |
| 80 km/h | 79.2 km/h | 50 mph | 49 mph |
| 100 km/h | 99.1 km/h | 62 mph | 62 mph |
| 120 km/h | 118.9 km/h | 75 mph | 74 mph |
Full comparison
215/55R16
Overall diameter642.9 mm · 25.31 in
Section width215 mm · 8.46 in
Sidewall height118.3 mm · 4.66 in
Circumference2019.7 mm · 79.5 in
Revolutions per mile797
Revolutions per km495
205/50R17
Overall diameter636.8 mm · 25.07 in
Section width205 mm · 8.07 in
Sidewall height102.5 mm · 4.04 in
Circumference2000.6 mm · 78.8 in
Revolutions per mile804
Revolutions per km500
-0.95%Safe swap — speedometer error is minor
Original
Overall diameter642.9 mm · 25.31 in
Sidewall height118.3 mm
Circumference2,019.7 mm
Revolutions / mile796.8
New
Overall diameter636.8 mm · 25.07 in
Sidewall height102.5 mm
Circumference2,000.6 mm
Revolutions / mile804.4
Speedometer & odometer error
The new tire changes overall diameter by -0.95%. 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 | 39.6 km/h | 25 mph | 25 mph |
| 60 km/h | 59.4 km/h | 37 mph | 37 mph |
| 80 km/h | 79.2 km/h | 50 mph | 49 mph |
| 100 km/h | 99.1 km/h | 62 mph | 62 mph |
| 120 km/h | 118.9 km/h | 75 mph | 74 mph |
See individual specs: 215/55R16 · 205/50R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.