+3.28%Borderline — noticeable speedometer/odometer error
Speedometer error
With a speedometer calibrated to 275/60R20, fitting 275/65R20 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 41.3 km/h | 25 mph | 26 mph |
| 60 km/h | 62.0 km/h | 37 mph | 39 mph |
| 80 km/h | 82.6 km/h | 50 mph | 51 mph |
| 100 km/h | 103.3 km/h | 62 mph | 64 mph |
| 120 km/h | 123.9 km/h | 75 mph | 77 mph |
Full comparison
275/60R20
Overall diameter838.0 mm · 32.99 in
Section width275 mm · 10.83 in
Sidewall height165.0 mm · 6.50 in
Circumference2632.7 mm · 103.6 in
Revolutions per mile611
Revolutions per km380
275/65R20
Overall diameter865.5 mm · 34.07 in
Section width275 mm · 10.83 in
Sidewall height178.8 mm · 7.04 in
Circumference2719.0 mm · 107.0 in
Revolutions per mile592
Revolutions per km368
+3.28%Borderline — noticeable speedometer/odometer error
Original
Overall diameter838 mm · 32.99 in
Sidewall height165 mm
Circumference2,632.7 mm
Revolutions / mile611.3
New
Overall diameter865.5 mm · 34.07 in
Sidewall height178.8 mm
Circumference2,719 mm
Revolutions / mile591.9
Speedometer & odometer error
The new tire changes overall diameter by +3.28%. 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 | 41.3 km/h | 25 mph | 26 mph |
| 60 km/h | 62 km/h | 37 mph | 39 mph |
| 80 km/h | 82.6 km/h | 50 mph | 51 mph |
| 100 km/h | 103.3 km/h | 62 mph | 64 mph |
| 120 km/h | 123.9 km/h | 75 mph | 77 mph |
See individual specs: 275/60R20 · 275/65R20. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.