215/55R18 vs 275/45R18
275/45R18 is a safe swap for 215/55R18 by the usual ±3% rule: the diameter differs by +1.59%.
Speedometer and odometer
With 275/45R18 on a car calibrated for 215/55R18, the speedometer reads 59.1 mph when you're really doing 60, and the odometer under-counts by 1.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.5 mph |
| 45 mph | 45.7 mph |
| 60 mph | 61.0 mph |
| 70 mph | 71.1 mph |
| 80 mph | 81.3 mph |
Other sizes close to 215/55R18
- 215/55R18 vs 225/45R18-4.90%
- 215/55R18 vs 245/45R18-2.31%
- 215/55R18 vs 235/50R18-0.22%
- 215/55R18 vs 235/55R18+3.17%
- 215/55R18 vs 235/45R18-3.60%
- 215/55R18 vs 235/55R17-0.49%
- 215/55R18 vs 225/60R18+4.83%
- 215/55R18 vs 225/50R18-1.66%
- 215/55R18 vs 225/55R18+1.59%
- 215/55R18 vs 255/40R18-4.69%
- 215/55R18 vs 215/60R17-0.56%
- 215/55R18 vs 245/50R18+1.23%
Questions
Can I replace 215/55R18 with 275/45R18?
275/45R18 is a safe swap for 215/55R18 by the usual ±3% rule: the diameter differs by +1.59%.
What's the difference between 215/55R18 and 275/45R18?
275/45R18 is 0.43" taller and 60 mm wider; the sidewall is +0.22". At an indicated 60 mph you'd actually be doing 61.0 mph.
Will 275/45R18 fit on 215/55R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.