255/55R18 vs 235/55R19
235/55R19 is a safe swap for 255/55R18 by the usual ±3% rule: the diameter differs by +0.46%.
Speedometer and odometer
With 235/55R19 on a car calibrated for 255/55R18, the speedometer reads 59.7 mph when you're really doing 60, and the odometer under-counts by 0.5%.
| 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 | 80.4 mph |
Other sizes close to 255/55R18
- 255/55R18 vs 235/60R18+0.20%
- 255/55R18 vs 235/55R18-2.98%
- 255/55R18 vs 235/65R17-0.05%
- 255/55R18 vs 225/60R18-1.42%
- 255/55R18 vs 255/50R19-0.01%
- 255/55R18 vs 245/60R18+1.83%
- 255/55R18 vs 225/55R18-4.47%
- 255/55R18 vs 235/65R18+3.39%
- 255/55R18 vs 245/50R18-4.81%
- 255/55R18 vs 255/60R18+3.46%
- 255/55R18 vs 245/55R18-1.49%
- 255/55R18 vs 255/60R17+0.01%
Questions
Can I replace 255/55R18 with 235/55R19?
235/55R19 is a safe swap for 255/55R18 by the usual ±3% rule: the diameter differs by +0.46%.
What's the difference between 255/55R18 and 235/55R19?
235/55R19 is 0.13" taller and 20 mm narrower; the sidewall is -0.43". At an indicated 60 mph you'd actually be doing 60.3 mph.
Will 235/55R19 fit on 255/55R18 wheels?
No — 255/55R18 needs a 18" wheel and 235/55R19 a 19" wheel. This is a plus/minus-size swap that changes wheels too.