225/55R17 vs 225/50R18
225/50R18 is a safe swap for 225/55R17 by the usual ±3% rule: the diameter differs by +0.43%.
Speedometer and odometer
With 225/50R18 on a car calibrated for 225/55R17, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.2 mph |
| 60 mph | 60.3 mph |
| 70 mph | 70.3 mph |
| 80 mph | 80.3 mph |
Other sizes close to 225/55R17
- 225/55R17 vs 225/50R17-3.31%
- 225/55R17 vs 245/45R18-0.24%
- 225/55R17 vs 235/55R17+1.62%
- 225/55R17 vs 215/55R17-1.62%
- 225/55R17 vs 225/60R17+3.31%
- 225/55R17 vs 215/50R17-4.78%
- 225/55R17 vs 245/45R17-3.97%
- 225/55R17 vs 215/65R16+0.97%
- 225/55R17 vs 215/65R17+4.71%
- 225/55R17 vs 215/60R17+1.55%
- 225/55R17 vs 205/65R16-0.94%
- 225/55R17 vs 225/60R16-0.43%
Questions
Can I replace 225/55R17 with 225/50R18?
225/50R18 is a safe swap for 225/55R17 by the usual ±3% rule: the diameter differs by +0.43%.
What's the difference between 225/55R17 and 225/50R18?
225/50R18 is 0.11" taller and 0 mm wider; the sidewall is -0.44". At an indicated 60 mph you'd actually be doing 60.3 mph.
Will 225/50R18 fit on 225/55R17 wheels?
No — 225/55R17 needs a 17" wheel and 225/50R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.