215/50R18 vs 275/45R18
275/45R18 is outside the ±3% rule as a replacement for 215/50R18: the diameter differs by +4.83%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 275/45R18 on a car calibrated for 215/50R18, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 4.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.5 mph |
| 45 mph | 47.2 mph |
| 60 mph | 62.9 mph |
| 70 mph | 73.4 mph |
| 80 mph | 83.9 mph |
Other sizes close to 215/50R18
- 215/50R18 vs 225/45R18-1.86%
- 215/50R18 vs 245/40R18-2.83%
- 215/50R18 vs 245/45R18+0.82%
- 215/50R18 vs 235/50R18+2.98%
- 215/50R18 vs 235/45R18-0.52%
- 215/50R18 vs 245/40R19+0.95%
- 215/50R18 vs 215/55R17-0.58%
- 215/50R18 vs 235/40R18-4.02%
- 215/50R18 vs 225/50R18+1.49%
- 215/50R18 vs 235/40R19-0.24%
- 215/50R18 vs 225/55R18+4.83%
- 215/50R18 vs 255/40R18-1.64%
Questions
Can I replace 215/50R18 with 275/45R18?
275/45R18 is outside the ±3% rule as a replacement for 215/50R18: the diameter differs by +4.83%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 215/50R18 and 275/45R18?
275/45R18 is 1.28" taller and 60 mm wider; the sidewall is +0.64". At an indicated 60 mph you'd actually be doing 62.9 mph.
Will 275/45R18 fit on 215/50R18 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.