The new tire changes overall diameter by -16.7%. 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 | 33.3 km/h | 25 mph | 21 mph |
| 60 km/h | 50 km/h | 37 mph | 31 mph |
| 80 km/h | 66.6 km/h | 50 mph | 41 mph |
| 100 km/h | 83.3 km/h | 62 mph | 52 mph |
| 120 km/h | 100 km/h | 75 mph | 62 mph |
Commonly compared with 305/40R22
- 305/40R22 vs 285/45R22 · 285/45R22 specs
- 305/40R22 vs 285/45R21 · 285/45R21 specs
- 305/40R22 vs 275/45R21 · 275/45R21 specs
- 305/40R22 vs 265/45R21 · 265/45R21 specs
- 305/40R22 vs 265/40R22 · 265/40R22 specs
- 305/40R22 vs 255/40R22 · 255/40R22 specs
- 305/40R22 vs 285/35R22 · 285/35R22 specs
- 305/40R22 vs 295/35R21 · 295/35R21 specs
FAQ
What is the overall diameter of a 305/40R22 tire?
A 305/40R22 tire has an overall diameter of about 31.61 inches (803 mm) and a section width of 305 mm.
What sizes can replace a 305/40R22 tire?
Sizes within about ±3% of 305/40R22's 31.6-inch diameter are the closest matches, such as 285/45R22, 285/45R21, 275/45R21. 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.