-4.68%Borderline — noticeable speedometer/odometer error
Speedometer error
With a speedometer calibrated to 275/70R18, fitting 265/70R17 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 38.1 km/h | 25 mph | 24 mph |
| 60 km/h | 57.2 km/h | 37 mph | 36 mph |
| 80 km/h | 76.3 km/h | 50 mph | 47 mph |
| 100 km/h | 95.3 km/h | 62 mph | 59 mph |
| 120 km/h | 114.4 km/h | 75 mph | 71 mph |
Full comparison
275/70R18
Overall diameter842.2 mm · 33.16 in
Section width275 mm · 10.83 in
Sidewall height192.5 mm · 7.58 in
Circumference2645.8 mm · 104.2 in
Revolutions per mile608
Revolutions per km378
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
-4.68%Borderline — noticeable speedometer/odometer error
Original
Overall diameter842.2 mm · 33.16 in
Sidewall height192.5 mm
Circumference2,645.8 mm
Revolutions / mile608.3
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 -4.68%. 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 | 38.1 km/h | 25 mph | 24 mph |
| 60 km/h | 57.2 km/h | 37 mph | 36 mph |
| 80 km/h | 76.3 km/h | 50 mph | 47 mph |
| 100 km/h | 95.3 km/h | 62 mph | 59 mph |
| 120 km/h | 114.4 km/h | 75 mph | 71 mph |
See individual specs: 275/70R18 · 265/70R17. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.