+1.46%Safe swap — speedometer error is minor
Speedometer error
With a speedometer calibrated to 245/55R19, fitting 255/55R19 makes it read as follows:
| Speedo shows | True speed | Speedo shows | True speed |
|---|---|---|---|
| 40 km/h | 40.6 km/h | 25 mph | 25 mph |
| 60 km/h | 60.9 km/h | 37 mph | 38 mph |
| 80 km/h | 81.2 km/h | 50 mph | 50 mph |
| 100 km/h | 101.5 km/h | 62 mph | 63 mph |
| 120 km/h | 121.8 km/h | 75 mph | 76 mph |
Full comparison
245/55R19
Overall diameter752.1 mm · 29.61 in
Section width245 mm · 9.65 in
Sidewall height134.8 mm · 5.31 in
Circumference2362.8 mm · 93.0 in
Revolutions per mile681
Revolutions per km423
255/55R19
Overall diameter763.1 mm · 30.04 in
Section width255 mm · 10.04 in
Sidewall height140.3 mm · 5.52 in
Circumference2397.3 mm · 94.4 in
Revolutions per mile671
Revolutions per km417
+1.46%Safe swap — speedometer error is minor
Original
Overall diameter752.1 mm · 29.61 in
Sidewall height134.8 mm
Circumference2,362.8 mm
Revolutions / mile681.1
New
Overall diameter763.1 mm · 30.04 in
Sidewall height140.3 mm
Circumference2,397.3 mm
Revolutions / mile671.3
Speedometer & odometer error
The new tire changes overall diameter by +1.46%. 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 | 40.6 km/h | 25 mph | 25 mph |
| 60 km/h | 60.9 km/h | 37 mph | 38 mph |
| 80 km/h | 81.2 km/h | 50 mph | 50 mph |
| 100 km/h | 101.5 km/h | 62 mph | 63 mph |
| 120 km/h | 121.8 km/h | 75 mph | 76 mph |
See individual specs: 245/55R19 · 255/55R19. A change this size can affect ABS/speed calibration — see wheel-speed codes if a light appears.