-2.05%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 215/70R15, fitting 205/70R15 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 | 58.8 km/h | 37 mph | 37 mph |
| 80 km/h | 78.4 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
215/70R15
Overall diameter682.0 mm · 26.85 in
Section width215 mm · 8.46 in
Sidewall height150.5 mm · 5.93 in
Circumference2142.6 mm · 84.4 in
Revolutions per mile751
Revolutions per km467
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
-2.05%Safe swap — speedometer error is minor
Original
Overall diameter682 mm · 26.85 in
Sidewall height150.5 mm
Circumference2,142.6 mm
Revolutions / mile751.1
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 -2.05%. 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 | 58.8 km/h | 37 mph | 37 mph |
| 80 km/h | 78.4 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: 215/70R15 · 205/70R15. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.