225/50R18 vs 225/55R18
225/55R18 is outside the ±3% rule as a replacement for 225/50R18: the diameter differs by +3.30%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 225/55R18 on a car calibrated for 225/50R18, the speedometer reads 58.1 mph when you're really doing 60, and the odometer under-counts by 3.3%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.0 mph |
| 45 mph | 46.5 mph |
| 60 mph | 62.0 mph |
| 70 mph | 72.3 mph |
| 80 mph | 82.6 mph |
Other sizes close to 225/50R18
- 225/50R18 vs 225/45R18-3.30%
- 225/50R18 vs 245/40R18-4.25%
- 225/50R18 vs 225/55R17-0.43%
- 225/50R18 vs 245/45R18-0.66%
- 225/50R18 vs 235/50R18+1.47%
- 225/50R18 vs 235/45R18-1.98%
- 225/50R18 vs 235/55R18+4.91%
- 225/50R18 vs 245/40R19-0.53%
- 225/50R18 vs 255/40R19+0.64%
- 225/50R18 vs 255/40R18-3.08%
- 225/50R18 vs 225/45R19+0.43%
- 225/50R18 vs 245/50R18+2.93%
Questions
Can I replace 225/50R18 with 225/55R18?
225/55R18 is outside the ±3% rule as a replacement for 225/50R18: the diameter differs by +3.30%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 225/50R18 and 225/55R18?
225/55R18 is 0.89" taller and 0 mm wider; the sidewall is +0.44". At an indicated 60 mph you'd actually be doing 62.0 mph.
Will 225/55R18 fit on 225/50R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 225 mm tire and the fender clearance.