235/50R18 vs 275/45R18
275/45R18 is a safe swap for 235/50R18 by the usual ±3% rule: the diameter differs by +1.81%.
Speedometer and odometer
With 275/45R18 on a car calibrated for 235/50R18, the speedometer reads 58.9 mph when you're really doing 60, and the odometer under-counts by 1.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.5 mph |
| 45 mph | 45.8 mph |
| 60 mph | 61.1 mph |
| 70 mph | 71.3 mph |
| 80 mph | 81.4 mph |
Other sizes close to 235/50R18
- 235/50R18 vs 225/45R18-4.70%
- 235/50R18 vs 245/45R18-2.09%
- 235/50R18 vs 235/45R18-3.39%
- 235/50R18 vs 235/55R18+3.39%
- 235/50R18 vs 235/55R17-0.27%
- 235/50R18 vs 225/50R18-1.44%
- 235/50R18 vs 255/40R19-0.81%
- 235/50R18 vs 225/55R18+1.81%
- 235/50R18 vs 255/40R18-4.48%
- 235/50R18 vs 215/60R17-0.35%
- 235/50R18 vs 245/50R18+1.44%
- 235/50R18 vs 255/45R18-0.79%
Questions
Can I replace 235/50R18 with 275/45R18?
275/45R18 is a safe swap for 235/50R18 by the usual ±3% rule: the diameter differs by +1.81%.
What's the difference between 235/50R18 and 275/45R18?
275/45R18 is 0.49" taller and 40 mm wider; the sidewall is +0.25". At an indicated 60 mph you'd actually be doing 61.1 mph.
Will 275/45R18 fit on 235/50R18 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.