235/55R18 vs 245/55R18
245/55R18 is a safe swap for 235/55R18 by the usual ±3% rule: the diameter differs by +1.54%.
Speedometer and odometer
With 245/55R18 on a car calibrated for 235/55R18, the speedometer reads 59.1 mph when you're really doing 60, and the odometer under-counts by 1.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.5 mph |
| 45 mph | 45.7 mph |
| 60 mph | 60.9 mph |
| 70 mph | 71.1 mph |
| 80 mph | 81.2 mph |
Other sizes close to 235/55R18
- 235/55R18 vs 235/60R18+3.28%
- 235/55R18 vs 235/50R18-3.28%
- 235/55R18 vs 225/60R18+1.61%
- 235/55R18 vs 225/50R18-4.68%
- 235/55R18 vs 245/60R18+4.96%
- 235/55R18 vs 225/55R18-1.54%
- 235/55R18 vs 255/55R18+3.07%
- 235/55R18 vs 255/45R19-0.50%
- 235/55R18 vs 235/60R17-0.27%
- 235/55R18 vs 215/65R17-0.61%
- 235/55R18 vs 245/50R18-1.89%
- 235/55R18 vs 235/50R19+0.27%
Questions
Can I replace 235/55R18 with 245/55R18?
245/55R18 is a safe swap for 235/55R18 by the usual ±3% rule: the diameter differs by +1.54%.
What's the difference between 235/55R18 and 245/55R18?
245/55R18 is 0.43" taller and 10 mm wider; the sidewall is +0.22". At an indicated 60 mph you'd actually be doing 60.9 mph.
Will 245/55R18 fit on 235/55R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 245 mm tire and the fender clearance.