+0.72%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 265/50R19, fitting 245/50R20 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 40.3 km/h | 25 mph | 25 mph |
| 60 km/h | 60.4 km/h | 37 mph | 38 mph |
| 80 km/h | 80.6 km/h | 50 mph | 50 mph |
| 100 km/h | 100.7 km/h | 62 mph | 63 mph |
| 120 km/h | 120.9 km/h | 75 mph | 75 mph |
Full comparison
265/50R19
Overall diameter747.6 mm · 29.43 in
Section width265 mm · 10.43 in
Sidewall height132.5 mm · 5.22 in
Circumference2348.7 mm · 92.5 in
Revolutions per mile685
Revolutions per km426
245/50R20
Overall diameter753.0 mm · 29.65 in
Section width245 mm · 9.65 in
Sidewall height122.5 mm · 4.82 in
Circumference2365.6 mm · 93.1 in
Revolutions per mile680
Revolutions per km423
+0.72%Safe swap — speedometer error is minor
Original
Overall diameter747.6 mm · 29.43 in
Sidewall height132.5 mm
Circumference2,348.7 mm
Revolutions / mile685.2
New
Overall diameter753 mm · 29.65 in
Sidewall height122.5 mm
Circumference2,365.6 mm
Revolutions / mile680.3
Speedometer & odometer error
The new tire changes overall diameter by +0.72%. 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 | 40.3 km/h | 25 mph | 25 mph |
| 60 km/h | 60.4 km/h | 37 mph | 38 mph |
| 80 km/h | 80.6 km/h | 50 mph | 50 mph |
| 100 km/h | 100.7 km/h | 62 mph | 63 mph |
| 120 km/h | 120.9 km/h | 75 mph | 75 mph |
See individual specs: 265/50R19 · 245/50R20. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.