+1.10%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 235/60R16, fitting 225/70R15 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 40.4 km/h | 25 mph | 25 mph |
| 60 km/h | 60.7 km/h | 37 mph | 38 mph |
| 80 km/h | 80.9 km/h | 50 mph | 50 mph |
| 100 km/h | 101.1 km/h | 62 mph | 63 mph |
| 120 km/h | 121.3 km/h | 75 mph | 75 mph |
Full comparison
235/60R16
Overall diameter688.4 mm · 27.10 in
Section width235 mm · 9.25 in
Sidewall height141.0 mm · 5.55 in
Circumference2162.7 mm · 85.1 in
Revolutions per mile744
Revolutions per km462
225/70R15
Overall diameter696.0 mm · 27.40 in
Section width225 mm · 8.86 in
Sidewall height157.5 mm · 6.20 in
Circumference2186.5 mm · 86.1 in
Revolutions per mile736
Revolutions per km457
+1.1%Safe swap — speedometer error is minor
Original
Overall diameter688.4 mm · 27.1 in
Sidewall height141 mm
Circumference2,162.7 mm
Revolutions / mile744.1
New
Overall diameter696 mm · 27.4 in
Sidewall height157.5 mm
Circumference2,186.5 mm
Revolutions / mile736
Speedometer & odometer error
The new tire changes overall diameter by +1.1%. 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 | 40.4 km/h | 25 mph | 25 mph |
| 60 km/h | 60.7 km/h | 37 mph | 38 mph |
| 80 km/h | 80.9 km/h | 50 mph | 50 mph |
| 100 km/h | 101.1 km/h | 62 mph | 63 mph |
| 120 km/h | 121.3 km/h | 75 mph | 75 mph |
See individual specs: 235/60R16 · 225/70R15. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.