315/35R22 vs 315/40R21
315/40R21 is a safe swap for 315/35R22 by the usual ±3% rule: the diameter differs by +0.78%.
Speedometer and odometer
With 315/40R21 on a car calibrated for 315/35R22, 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 | 30.2 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.5 mph |
| 80 mph | 80.6 mph |
Other sizes close to 315/35R22
- 315/35R22 vs 285/45R22+4.62%
- 315/35R22 vs 275/40R22-0.06%
- 315/35R22 vs 275/45R21+0.21%
- 315/35R22 vs 265/40R22-1.09%
- 315/35R22 vs 265/35R22-4.49%
- 315/35R22 vs 285/35R22-2.69%
- 315/35R22 vs 285/40R22+0.96%
- 315/35R22 vs 265/45R21-0.95%
- 315/35R22 vs 275/45R22+3.46%
- 315/35R22 vs 305/40R22+3.02%
- 315/35R22 vs 275/35R22-3.59%
- 315/35R22 vs 325/35R22+0.90%
Questions
Can I replace 315/35R22 with 315/40R21?
315/40R21 is a safe swap for 315/35R22 by the usual ±3% rule: the diameter differs by +0.78%.
What's the difference between 315/35R22 and 315/40R21?
315/40R21 is 0.24" taller and 0 mm wider; the sidewall is +0.62". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 315/40R21 fit on 315/35R22 wheels?
No — 315/35R22 needs a 22" wheel and 315/40R21 a 21" wheel. This is a plus/minus-size swap that changes wheels too.