-1.90%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 235/70R16, fitting 225/70R16 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 | 58.9 km/h | 37 mph | 37 mph |
| 80 km/h | 78.5 km/h | 50 mph | 49 mph |
| 100 km/h | 98.1 km/h | 62 mph | 61 mph |
| 120 km/h | 117.7 km/h | 75 mph | 73 mph |
Full comparison
235/70R16
Overall diameter735.4 mm · 28.95 in
Section width235 mm · 9.25 in
Sidewall height164.5 mm · 6.48 in
Circumference2310.3 mm · 91.0 in
Revolutions per mile697
Revolutions per km433
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
-1.9%Safe swap — speedometer error is minor
Original
Overall diameter735.4 mm · 28.95 in
Sidewall height164.5 mm
Circumference2,310.3 mm
Revolutions / mile696.6
New
Overall diameter721.4 mm · 28.4 in
Sidewall height157.5 mm
Circumference2,266.3 mm
Revolutions / mile710.1
Speedometer & odometer error
The new tire changes overall diameter by -1.9%. 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 | 58.9 km/h | 37 mph | 37 mph |
| 80 km/h | 78.5 km/h | 50 mph | 49 mph |
| 100 km/h | 98.1 km/h | 62 mph | 61 mph |
| 120 km/h | 117.7 km/h | 75 mph | 73 mph |
See individual specs: 235/70R16 · 225/70R16. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.