225/50R18 vs 255/40R19
255/40R19 is a safe swap for 225/50R18 by the usual ±3% rule: the diameter differs by +0.64%.
Speedometer and odometer
With 255/40R19 on a car calibrated for 225/50R18, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.3 mph |
| 60 mph | 60.4 mph |
| 70 mph | 70.5 mph |
| 80 mph | 80.5 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 225/55R18+3.30%
- 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 255/40R19?
255/40R19 is a safe swap for 225/50R18 by the usual ±3% rule: the diameter differs by +0.64%.
What's the difference between 225/50R18 and 255/40R19?
255/40R19 is 0.17" taller and 30 mm wider; the sidewall is -0.41". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 255/40R19 fit on 225/50R18 wheels?
No — 225/50R18 needs a 18" wheel and 255/40R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.