-0.38%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 225/45R17, fitting 205/55R16 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.8 km/h | 25 mph | 25 mph |
| 60 km/h | 59.8 km/h | 37 mph | 37 mph |
| 80 km/h | 79.7 km/h | 50 mph | 50 mph |
| 100 km/h | 99.6 km/h | 62 mph | 62 mph |
| 120 km/h | 119.5 km/h | 75 mph | 74 mph |
Full comparison
225/45R17
Overall diameter634.3 mm · 24.97 in
Section width225 mm · 8.86 in
Sidewall height101.3 mm · 3.99 in
Circumference1992.7 mm · 78.5 in
Revolutions per mile808
Revolutions per km502
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
-0.38%Safe swap — speedometer error is minor
Original
Overall diameter634.3 mm · 24.97 in
Sidewall height101.3 mm
Circumference1,992.7 mm
Revolutions / mile807.6
New
Overall diameter631.9 mm · 24.88 in
Sidewall height112.8 mm
Circumference1,985.2 mm
Revolutions / mile810.7
Speedometer & odometer error
The new tire changes overall diameter by -0.38%. 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 | 39.8 km/h | 25 mph | 25 mph |
| 60 km/h | 59.8 km/h | 37 mph | 37 mph |
| 80 km/h | 79.7 km/h | 50 mph | 50 mph |
| 100 km/h | 99.6 km/h | 62 mph | 62 mph |
| 120 km/h | 119.5 km/h | 75 mph | 74 mph |
See individual specs: 225/45R17 · 205/55R16. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.