255/40R18 vs 225/40R19
225/40R19 is a safe swap for 255/40R18 by the usual ±3% rule: the diameter differs by +0.21%.
Speedometer and odometer
With 225/40R19 on a car calibrated for 255/40R18, the speedometer reads 59.9 mph when you're really doing 60, and the odometer under-counts by 0.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.1 mph |
| 70 mph | 70.1 mph |
| 80 mph | 80.2 mph |
Other sizes close to 255/40R18
- 255/40R18 vs 225/45R18-0.23%
- 255/40R18 vs 245/40R18-1.21%
- 255/40R18 vs 225/40R18-3.63%
- 255/40R18 vs 225/50R17-0.67%
- 255/40R18 vs 245/45R18+2.50%
- 255/40R18 vs 235/50R18+4.69%
- 255/40R18 vs 235/45R18+1.13%
- 255/40R18 vs 235/40R18-2.42%
- 255/40R18 vs 225/50R18+3.18%
- 255/40R18 vs 255/35R19-0.02%
- 255/40R18 vs 255/35R18-3.86%
- 255/40R18 vs 275/35R18-1.74%
Questions
Can I replace 255/40R18 with 225/40R19?
225/40R19 is a safe swap for 255/40R18 by the usual ±3% rule: the diameter differs by +0.21%.
What's the difference between 255/40R18 and 225/40R19?
225/40R19 is 0.06" taller and 30 mm narrower; the sidewall is -0.47". At an indicated 60 mph you'd actually be doing 60.1 mph.
Will 225/40R19 fit on 255/40R18 wheels?
No — 255/40R18 needs a 18" wheel and 225/40R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.