275/40R22 vs 315/40R21
315/40R21 is a safe swap for 275/40R22 by the usual ±3% rule: the diameter differs by +0.85%.
Speedometer and odometer
With 315/40R21 on a car calibrated for 275/40R22, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.3 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.7 mph |
Other sizes close to 275/40R22
- 275/40R22 vs 285/45R22+4.69%
- 275/40R22 vs 275/45R21+0.27%
- 275/40R22 vs 265/40R22-1.03%
- 275/40R22 vs 265/35R22-4.43%
- 275/40R22 vs 285/35R22-2.63%
- 275/40R22 vs 285/40R22+1.03%
- 275/40R22 vs 265/45R21-0.89%
- 275/40R22 vs 275/45R22+3.53%
- 275/40R22 vs 305/40R22+3.08%
- 275/40R22 vs 275/35R22-3.53%
- 275/40R22 vs 315/35R22+0.06%
- 275/40R22 vs 325/35R22+0.96%
Questions
Can I replace 275/40R22 with 315/40R21?
315/40R21 is a safe swap for 275/40R22 by the usual ±3% rule: the diameter differs by +0.85%.
What's the difference between 275/40R22 and 315/40R21?
315/40R21 is 0.26" taller and 40 mm wider; the sidewall is +0.63". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 315/40R21 fit on 275/40R22 wheels?
No — 275/40R22 needs a 22" wheel and 315/40R21 a 21" wheel. This is a plus/minus-size swap that changes wheels too.