-1.24%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 225/60R16, fitting 205/70R15 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.5 km/h | 25 mph | 25 mph |
| 60 km/h | 59.3 km/h | 37 mph | 37 mph |
| 80 km/h | 79.0 km/h | 50 mph | 49 mph |
| 100 km/h | 98.8 km/h | 62 mph | 61 mph |
| 120 km/h | 118.5 km/h | 75 mph | 74 mph |
Full comparison
225/60R16
Overall diameter676.4 mm · 26.63 in
Section width225 mm · 8.86 in
Sidewall height135.0 mm · 5.31 in
Circumference2125.0 mm · 83.7 in
Revolutions per mile757
Revolutions per km471
205/70R15
Overall diameter668.0 mm · 26.30 in
Section width205 mm · 8.07 in
Sidewall height143.5 mm · 5.65 in
Circumference2098.6 mm · 82.6 in
Revolutions per mile767
Revolutions per km477
-1.24%Safe swap — speedometer error is minor
Original
Overall diameter676.4 mm · 26.63 in
Sidewall height135 mm
Circumference2,125 mm
Revolutions / mile757.3
New
Overall diameter668 mm · 26.3 in
Sidewall height143.5 mm
Circumference2,098.6 mm
Revolutions / mile766.9
Speedometer & odometer error
The new tire changes overall diameter by -1.24%. 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 | 39.5 km/h | 25 mph | 25 mph |
| 60 km/h | 59.3 km/h | 37 mph | 37 mph |
| 80 km/h | 79 km/h | 50 mph | 49 mph |
| 100 km/h | 98.8 km/h | 62 mph | 61 mph |
| 120 km/h | 118.5 km/h | 75 mph | 74 mph |
See individual specs: 225/60R16 · 205/70R15. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.