+3.79%Borderline — noticeable speedometer/odometer error
Speedometer error
With a speedometer calibrated to 235/70R16, fitting 255/65R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 41.5 km/h | 25 mph | 26 mph |
| 60 km/h | 62.3 km/h | 37 mph | 39 mph |
| 80 km/h | 83.0 km/h | 50 mph | 52 mph |
| 100 km/h | 103.8 km/h | 62 mph | 64 mph |
| 120 km/h | 124.6 km/h | 75 mph | 77 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
255/65R17
Overall diameter763.3 mm · 30.05 in
Section width255 mm · 10.04 in
Sidewall height165.8 mm · 6.53 in
Circumference2398.0 mm · 94.4 in
Revolutions per mile671
Revolutions per km417
+3.79%Borderline — noticeable speedometer/odometer error
Original
Overall diameter735.4 mm · 28.95 in
Sidewall height164.5 mm
Circumference2,310.3 mm
Revolutions / mile696.6
New
Overall diameter763.3 mm · 30.05 in
Sidewall height165.8 mm
Circumference2,398 mm
Revolutions / mile671.1
Speedometer & odometer error
The new tire changes overall diameter by +3.79%. 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 | 41.5 km/h | 25 mph | 26 mph |
| 60 km/h | 62.3 km/h | 37 mph | 39 mph |
| 80 km/h | 83 km/h | 50 mph | 52 mph |
| 100 km/h | 103.8 km/h | 62 mph | 64 mph |
| 120 km/h | 124.6 km/h | 75 mph | 77 mph |
See individual specs: 235/70R16 · 255/65R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.