-8.02%Not recommended — recalibrate the speedometer
Speedometer error
With a speedometer calibrated to 315/70R17, fitting 265/70R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 36.8 km/h | 25 mph | 23 mph |
| 60 km/h | 55.2 km/h | 37 mph | 34 mph |
| 80 km/h | 73.6 km/h | 50 mph | 46 mph |
| 100 km/h | 92.0 km/h | 62 mph | 57 mph |
| 120 km/h | 110.4 km/h | 75 mph | 69 mph |
Full comparison
315/70R17
Overall diameter872.8 mm · 34.36 in
Section width315 mm · 12.40 in
Sidewall height220.5 mm · 8.68 in
Circumference2742.0 mm · 108.0 in
Revolutions per mile587
Revolutions per km365
265/70R17
Overall diameter802.8 mm · 31.61 in
Section width265 mm · 10.43 in
Sidewall height185.5 mm · 7.30 in
Circumference2522.1 mm · 99.3 in
Revolutions per mile638
Revolutions per km396
-8.02%Not recommended — recalibrate the speedometer
Original
Overall diameter872.8 mm · 34.36 in
Sidewall height220.5 mm
Circumference2,742 mm
Revolutions / mile586.9
New
Overall diameter802.8 mm · 31.61 in
Sidewall height185.5 mm
Circumference2,522.1 mm
Revolutions / mile638.1
Speedometer & odometer error
The new tire changes overall diameter by -8.02%. 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 | 36.8 km/h | 25 mph | 23 mph |
| 60 km/h | 55.2 km/h | 37 mph | 34 mph |
| 80 km/h | 73.6 km/h | 50 mph | 46 mph |
| 100 km/h | 92 km/h | 62 mph | 57 mph |
| 120 km/h | 110.4 km/h | 75 mph | 69 mph |
See individual specs: 315/70R17 · 265/70R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.