225/60R18 vs 255/60R18
255/60R18 is outside the ±3% rule as a replacement for 225/60R18: the diameter differs by +4.95%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 255/60R18 on a car calibrated for 225/60R18, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 5.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.5 mph |
| 45 mph | 47.2 mph |
| 60 mph | 63.0 mph |
| 70 mph | 73.5 mph |
| 80 mph | 84.0 mph |
Other sizes close to 225/60R18
- 225/60R18 vs 235/60R18+1.65%
- 225/60R18 vs 225/65R17-0.40%
- 225/60R18 vs 235/50R18-4.81%
- 225/60R18 vs 235/55R18-1.58%
- 225/60R18 vs 245/60R18+3.30%
- 225/60R18 vs 225/55R18-3.09%
- 225/60R18 vs 255/55R18+1.44%
- 225/60R18 vs 235/65R18+4.88%
- 225/60R18 vs 225/55R19+0.40%
- 225/60R18 vs 245/50R18-3.44%
- 225/60R18 vs 215/55R18-4.61%
- 225/60R18 vs 245/50R19+0.06%
Questions
Can I replace 225/60R18 with 255/60R18?
255/60R18 is outside the ±3% rule as a replacement for 225/60R18: the diameter differs by +4.95%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 225/60R18 and 255/60R18?
255/60R18 is 1.42" taller and 30 mm wider; the sidewall is +0.71". At an indicated 60 mph you'd actually be doing 63.0 mph.
Will 255/60R18 fit on 225/60R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.