295/30R22 vs 255/40R21
255/40R21 is a safe swap for 295/30R22 by the usual ±3% rule: the diameter differs by +0.22%.
Speedometer and odometer
With 255/40R21 on a car calibrated for 295/30R22, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.1 mph |
| 70 mph | 70.2 mph |
| 80 mph | 80.2 mph |
Other sizes close to 295/30R22
- 295/30R22 vs 295/35R21+0.56%
- 295/30R22 vs 265/40R22+4.76%
- 295/30R22 vs 265/35R22+1.16%
- 295/30R22 vs 285/35R22+3.06%
- 295/30R22 vs 285/35R21-0.39%
- 295/30R22 vs 245/40R21-0.87%
- 295/30R22 vs 275/35R22+2.11%
- 295/30R22 vs 295/35R22+4.01%
- 295/30R22 vs 285/30R22-0.82%
- 295/30R22 vs 315/30R22+1.63%
- 295/30R22 vs 255/40R22+3.67%
- 295/30R22 vs 265/30R22-2.45%
Questions
Can I replace 295/30R22 with 255/40R21?
255/40R21 is a safe swap for 295/30R22 by the usual ±3% rule: the diameter differs by +0.22%.
What's the difference between 295/30R22 and 255/40R21?
255/40R21 is 0.06" taller and 40 mm narrower; the sidewall is +0.53". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 255/40R21 fit on 295/30R22 wheels?
No — 295/30R22 needs a 22" wheel and 255/40R21 a 21" wheel. This is a plus/minus-size swap that changes wheels too.