255/40R22 vs 305/40R22
305/40R22 is outside the ±3% rule as a replacement for 255/40R22: the diameter differs by +5.24%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 305/40R22 on a car calibrated for 255/40R22, the speedometer reads 57.0 mph when you're really doing 60, and the odometer under-counts by 5.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.6 mph |
| 45 mph | 47.4 mph |
| 60 mph | 63.1 mph |
| 70 mph | 73.7 mph |
| 80 mph | 84.2 mph |
Other sizes close to 255/40R22
- 255/40R22 vs 275/40R22+2.10%
- 255/40R22 vs 265/40R22+1.05%
- 255/40R22 vs 265/35R22-2.43%
- 255/40R22 vs 285/35R22-0.59%
- 255/40R22 vs 285/40R22+3.15%
- 255/40R22 vs 295/40R21+0.87%
- 255/40R22 vs 285/40R21-0.18%
- 255/40R22 vs 275/35R22-1.51%
- 255/40R22 vs 295/35R22+0.33%
- 255/40R22 vs 315/35R22+2.16%
- 255/40R22 vs 325/35R22+3.08%
- 255/40R22 vs 285/30R22-4.33%
Questions
Can I replace 255/40R22 with 305/40R22?
305/40R22 is outside the ±3% rule as a replacement for 255/40R22: the diameter differs by +5.24%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 255/40R22 and 305/40R22?
305/40R22 is 1.57" taller and 50 mm wider; the sidewall is +0.79". At an indicated 60 mph you'd actually be doing 63.1 mph.
Will 305/40R22 fit on 255/40R22 wheels?
Both use a 22" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.