255/55R18 vs 245/60R18
245/60R18 is a safe swap for 255/55R18 by the usual ±3% rule: the diameter differs by +1.83%.
Speedometer and odometer
With 245/60R18 on a car calibrated for 255/55R18, 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 | 81.5 mph |
Other sizes close to 255/55R18
- 255/55R18 vs 235/60R18+0.20%
- 255/55R18 vs 235/55R19+0.46%
- 255/55R18 vs 235/55R18-2.98%
- 255/55R18 vs 235/65R17-0.05%
- 255/55R18 vs 225/60R18-1.42%
- 255/55R18 vs 255/50R19-0.01%
- 255/55R18 vs 225/55R18-4.47%
- 255/55R18 vs 235/65R18+3.39%
- 255/55R18 vs 245/50R18-4.81%
- 255/55R18 vs 255/60R18+3.46%
- 255/55R18 vs 245/55R18-1.49%
- 255/55R18 vs 255/60R17+0.01%
Questions
Can I replace 255/55R18 with 245/60R18?
245/60R18 is a safe swap for 255/55R18 by the usual ±3% rule: the diameter differs by +1.83%.
What's the difference between 255/55R18 and 245/60R18?
245/60R18 is 0.53" taller and 10 mm narrower; the sidewall is +0.27". At an indicated 60 mph you'd actually be doing 61.1 mph.
Will 245/60R18 fit on 255/55R18 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.