+0.78%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 205/55R16, fitting 205/50R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 40.3 km/h | 25 mph | 25 mph |
| 60 km/h | 60.5 km/h | 37 mph | 38 mph |
| 80 km/h | 80.6 km/h | 50 mph | 50 mph |
| 100 km/h | 100.8 km/h | 62 mph | 63 mph |
| 120 km/h | 120.9 km/h | 75 mph | 75 mph |
Full comparison
205/55R16
Overall diameter631.9 mm · 24.88 in
Section width205 mm · 8.07 in
Sidewall height112.8 mm · 4.44 in
Circumference1985.2 mm · 78.2 in
Revolutions per mile811
Revolutions per km504
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
+0.78%Safe swap — speedometer error is minor
Original
Overall diameter631.9 mm · 24.88 in
Sidewall height112.8 mm
Circumference1,985.2 mm
Revolutions / mile810.7
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 +0.78%. 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 | 40.3 km/h | 25 mph | 25 mph |
| 60 km/h | 60.5 km/h | 37 mph | 38 mph |
| 80 km/h | 80.6 km/h | 50 mph | 50 mph |
| 100 km/h | 100.8 km/h | 62 mph | 63 mph |
| 120 km/h | 120.9 km/h | 75 mph | 75 mph |
See individual specs: 205/55R16 · 205/50R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.