315/30R22 vs 255/40R22
255/40R22 is a safe swap for 315/30R22 by the usual ±3% rule: the diameter differs by +2.01%.
Speedometer and odometer
With 255/40R22 on a car calibrated for 315/30R22, the speedometer reads 58.8 mph when you're really doing 60, and the odometer under-counts by 2.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.6 mph |
| 45 mph | 45.9 mph |
| 60 mph | 61.2 mph |
| 70 mph | 71.4 mph |
| 80 mph | 81.6 mph |
Other sizes close to 315/30R22
- 315/30R22 vs 265/40R21-0.32%
- 315/30R22 vs 275/40R22+4.15%
- 315/30R22 vs 265/40R22+3.08%
- 315/30R22 vs 265/35R22-0.47%
- 315/30R22 vs 285/35R22+1.40%
- 315/30R22 vs 275/40R21+0.75%
- 315/30R22 vs 315/35R21+0.82%
- 315/30R22 vs 275/35R22+0.47%
- 315/30R22 vs 295/35R22+2.34%
- 315/30R22 vs 315/35R22+4.21%
- 315/30R22 vs 285/30R22-2.41%
- 315/30R22 vs 295/30R22-1.60%
Questions
Can I replace 315/30R22 with 255/40R22?
255/40R22 is a safe swap for 315/30R22 by the usual ±3% rule: the diameter differs by +2.01%.
What's the difference between 315/30R22 and 255/40R22?
255/40R22 is 0.59" taller and 60 mm narrower; the sidewall is +0.30". At an indicated 60 mph you'd actually be doing 61.2 mph.
Will 255/40R22 fit on 315/30R22 wheels?
Both use a 22" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.