-1.55%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 215/50R17, fitting 205/50R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.4 km/h | 25 mph | 24 mph |
| 60 km/h | 59.1 km/h | 37 mph | 37 mph |
| 80 km/h | 78.8 km/h | 50 mph | 49 mph |
| 100 km/h | 98.5 km/h | 62 mph | 61 mph |
| 120 km/h | 118.1 km/h | 75 mph | 73 mph |
Full comparison
215/50R17
Overall diameter646.8 mm · 25.46 in
Section width215 mm · 8.46 in
Sidewall height107.5 mm · 4.23 in
Circumference2032.0 mm · 80.0 in
Revolutions per mile792
Revolutions per km492
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
-1.55%Safe swap — speedometer error is minor
Original
Overall diameter646.8 mm · 25.46 in
Sidewall height107.5 mm
Circumference2,032 mm
Revolutions / mile792
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 -1.55%. 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 | 39.4 km/h | 25 mph | 24 mph |
| 60 km/h | 59.1 km/h | 37 mph | 37 mph |
| 80 km/h | 78.8 km/h | 50 mph | 49 mph |
| 100 km/h | 98.5 km/h | 62 mph | 61 mph |
| 120 km/h | 118.1 km/h | 75 mph | 73 mph |
See individual specs: 215/50R17 · 205/50R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.