+1.68%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 225/70R16, fitting 235/75R15 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 40.7 km/h | 25 mph | 25 mph |
| 60 km/h | 61.0 km/h | 37 mph | 38 mph |
| 80 km/h | 81.3 km/h | 50 mph | 51 mph |
| 100 km/h | 101.7 km/h | 62 mph | 63 mph |
| 120 km/h | 122.0 km/h | 75 mph | 76 mph |
Full comparison
225/70R16
Overall diameter721.4 mm · 28.40 in
Section width225 mm · 8.86 in
Sidewall height157.5 mm · 6.20 in
Circumference2266.3 mm · 89.2 in
Revolutions per mile710
Revolutions per km441
235/75R15
Overall diameter733.5 mm · 28.88 in
Section width235 mm · 9.25 in
Sidewall height176.3 mm · 6.94 in
Circumference2304.4 mm · 90.7 in
Revolutions per mile698
Revolutions per km434
+1.68%Safe swap — speedometer error is minor
Original
Overall diameter721.4 mm · 28.4 in
Sidewall height157.5 mm
Circumference2,266.3 mm
Revolutions / mile710.1
New
Overall diameter733.5 mm · 28.88 in
Sidewall height176.3 mm
Circumference2,304.4 mm
Revolutions / mile698.4
Speedometer & odometer error
The new tire changes overall diameter by +1.68%. 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 | 40.7 km/h | 25 mph | 25 mph |
| 60 km/h | 61 km/h | 37 mph | 38 mph |
| 80 km/h | 81.3 km/h | 50 mph | 51 mph |
| 100 km/h | 101.7 km/h | 62 mph | 63 mph |
| 120 km/h | 122 km/h | 75 mph | 76 mph |
See individual specs: 225/70R16 · 235/75R15. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.