215/45R18 vs 275/40R17
275/40R17 is a safe swap for 215/45R18 by the usual ±3% rule: the diameter differs by +0.17%.
Speedometer and odometer
With 275/40R17 on a car calibrated for 215/45R18, 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 | 70.1 mph |
| 80 mph | 80.1 mph |
Other sizes close to 215/45R18
- 215/45R18 vs 245/40R18+0.38%
- 215/45R18 vs 225/45R18+1.38%
- 215/45R18 vs 225/40R18-2.07%
- 215/45R18 vs 225/50R17+0.94%
- 215/45R18 vs 245/45R18+4.15%
- 215/45R18 vs 235/45R18+2.77%
- 215/45R18 vs 235/40R18-0.85%
- 215/45R18 vs 225/50R18+4.84%
- 215/45R18 vs 215/50R17-0.60%
- 215/45R18 vs 245/45R17+0.25%
- 215/45R18 vs 255/35R18-2.31%
- 215/45R18 vs 255/40R18+1.61%
Questions
Can I replace 215/45R18 with 275/40R17?
275/40R17 is a safe swap for 215/45R18 by the usual ±3% rule: the diameter differs by +0.17%.
What's the difference between 215/45R18 and 275/40R17?
275/40R17 is 0.04" taller and 60 mm wider; the sidewall is +0.52". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 275/40R17 fit on 215/45R18 wheels?
No — 215/45R18 needs a 18" wheel and 275/40R17 a 17" wheel. This is a plus/minus-size swap that changes wheels too.