245/50R18 vs 235/55R18
235/55R18 is a safe swap for 245/50R18 by the usual ±3% rule: the diameter differs by +1.92%.
Speedometer and odometer
With 235/55R18 on a car calibrated for 245/50R18, the speedometer reads 58.9 mph when you're really doing 60, and the odometer under-counts by 1.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.6 mph |
| 45 mph | 45.9 mph |
| 60 mph | 61.2 mph |
| 70 mph | 71.3 mph |
| 80 mph | 81.5 mph |
Other sizes close to 245/50R18
- 245/50R18 vs 245/45R18-3.49%
- 245/50R18 vs 235/50R18-1.42%
- 245/50R18 vs 235/45R18-4.77%
- 245/50R18 vs 245/45R19+0.13%
- 245/50R18 vs 225/60R18+3.56%
- 245/50R18 vs 225/50R18-2.85%
- 245/50R18 vs 225/60R17-0.06%
- 245/50R18 vs 225/55R18+0.36%
- 245/50R18 vs 275/40R19+0.06%
- 245/50R18 vs 255/45R18-2.21%
- 245/50R18 vs 215/55R18-1.21%
- 245/50R18 vs 275/40R18-3.56%
Questions
Can I replace 245/50R18 with 235/55R18?
235/55R18 is a safe swap for 245/50R18 by the usual ±3% rule: the diameter differs by +1.92%.
What's the difference between 245/50R18 and 235/55R18?
235/55R18 is 0.53" taller and 10 mm narrower; the sidewall is +0.27". At an indicated 60 mph you'd actually be doing 61.2 mph.
Will 235/55R18 fit on 245/50R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 235 mm tire and the fender clearance.