-5.06%Not recommended — recalibrate the speedometer
Speedometer error
With a speedometer calibrated to 215/70R15, fitting 205/65R15 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 38.0 km/h | 25 mph | 24 mph |
| 60 km/h | 57.0 km/h | 37 mph | 35 mph |
| 80 km/h | 76.0 km/h | 50 mph | 47 mph |
| 100 km/h | 94.9 km/h | 62 mph | 59 mph |
| 120 km/h | 113.9 km/h | 75 mph | 71 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
205/65R15
Overall diameter647.5 mm · 25.49 in
Section width205 mm · 8.07 in
Sidewall height133.3 mm · 5.25 in
Circumference2034.2 mm · 80.1 in
Revolutions per mile791
Revolutions per km492
-5.06%Not recommended — recalibrate the speedometer
Original
Overall diameter682 mm · 26.85 in
Sidewall height150.5 mm
Circumference2,142.6 mm
Revolutions / mile751.1
New
Overall diameter647.5 mm · 25.49 in
Sidewall height133.3 mm
Circumference2,034.2 mm
Revolutions / mile791.2
Speedometer & odometer error
The new tire changes overall diameter by -5.06%. 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 | 38 km/h | 25 mph | 24 mph |
| 60 km/h | 57 km/h | 37 mph | 35 mph |
| 80 km/h | 76 km/h | 50 mph | 47 mph |
| 100 km/h | 94.9 km/h | 62 mph | 59 mph |
| 120 km/h | 113.9 km/h | 75 mph | 71 mph |
See individual specs: 215/70R15 · 205/65R15. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.