275/40R22 vs 275/45R21
275/45R21 is a safe swap for 275/40R22 by the usual ±3% rule: the diameter differs by +0.27%.
Speedometer and odometer
With 275/45R21 on a car calibrated for 275/40R22, the speedometer reads 59.8 mph when you're really doing 60, and the odometer under-counts by 0.3%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.2 mph |
| 70 mph | 70.2 mph |
| 80 mph | 80.2 mph |
Other sizes close to 275/40R22
- 275/40R22 vs 285/45R22+4.69%
- 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 315/40R21+0.85%
- 275/40R22 vs 315/35R22+0.06%
- 275/40R22 vs 325/35R22+0.96%
Questions
Can I replace 275/40R22 with 275/45R21?
275/45R21 is a safe swap for 275/40R22 by the usual ±3% rule: the diameter differs by +0.27%.
What's the difference between 275/40R22 and 275/45R21?
275/45R21 is 0.08" taller and 0 mm wider; the sidewall is +0.54". At an indicated 60 mph you'd actually be doing 60.2 mph.
Will 275/45R21 fit on 275/40R22 wheels?
No — 275/40R22 needs a 22" wheel and 275/45R21 a 21" wheel. This is a plus/minus-size swap that changes wheels too.