The new tire changes overall diameter by -2.61%. 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 | 39 km/h | 25 mph | 24 mph |
| 60 km/h | 58.4 km/h | 37 mph | 36 mph |
| 80 km/h | 77.9 km/h | 50 mph | 48 mph |
| 100 km/h | 97.4 km/h | 62 mph | 61 mph |
| 120 km/h | 116.9 km/h | 75 mph | 73 mph |
Commonly compared with 255/40R19
- 255/40R19 vs 255/45R18 · 255/45R18 specs
- 255/40R19 vs 235/50R18 · 235/50R18 specs
- 255/40R19 vs 245/40R19 · 245/40R19 specs
- 255/40R19 vs 245/45R18 · 245/45R18 specs
- 255/40R19 vs 235/40R19 · 235/40R19 specs
- 255/40R19 vs 275/40R19 · 275/40R19 specs
- 255/40R19 vs 245/45R19 · 245/45R19 specs
- 255/40R19 vs 245/40R20 · 245/40R20 specs
FAQ
What is the overall diameter of a 255/40R19 tire?
A 255/40R19 tire has an overall diameter of about 27.03 inches (687 mm) and a section width of 255 mm.
What sizes can replace a 255/40R19 tire?
Sizes within about ±3% of 255/40R19's 27.0-inch diameter are the closest matches, such as 255/45R18, 235/50R18, 245/40R19. Use the calculator above to check the exact speedometer effect of any substitute.
Fitment & trouble codes
Changing tire size by more than about 3% shifts the speedometer, odometer and, on some vehicles, ABS/traction calibration — which can set wheel-speed-sensor or vehicle-speed codes. See C1234 (wheel speed sensor) and C0050 (rear wheel speed) if a warning light appears after a size change.