-2.12%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 245/70R16, fitting 235/75R15 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 39.2 km/h | 25 mph | 24 mph |
| 60 km/h | 58.7 km/h | 37 mph | 36 mph |
| 80 km/h | 78.3 km/h | 50 mph | 49 mph |
| 100 km/h | 97.9 km/h | 62 mph | 61 mph |
| 120 km/h | 117.5 km/h | 75 mph | 73 mph |
Full comparison
245/70R16
Overall diameter749.4 mm · 29.50 in
Section width245 mm · 9.65 in
Sidewall height171.5 mm · 6.75 in
Circumference2354.3 mm · 92.7 in
Revolutions per mile684
Revolutions per km425
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
-2.12%Safe swap — speedometer error is minor
Original
Overall diameter749.4 mm · 29.5 in
Sidewall height171.5 mm
Circumference2,354.3 mm
Revolutions / mile683.6
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 -2.12%. 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 | 39.2 km/h | 25 mph | 24 mph |
| 60 km/h | 58.7 km/h | 37 mph | 36 mph |
| 80 km/h | 78.3 km/h | 50 mph | 49 mph |
| 100 km/h | 97.9 km/h | 62 mph | 61 mph |
| 120 km/h | 117.5 km/h | 75 mph | 73 mph |
See individual specs: 245/70R16 · 235/75R15. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.