255/50R19 vs 235/50R20
235/50R20 is a safe swap for 255/50R19 by the usual ±3% rule: the diameter differs by +0.73%.
Speedometer and odometer
With 235/50R20 on a car calibrated for 255/50R19, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.7%.
| 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 | 80.6 mph |
Other sizes close to 255/50R19
- 255/50R19 vs 235/60R18+0.22%
- 255/50R19 vs 235/55R19+0.47%
- 255/50R19 vs 245/45R19-4.68%
- 255/50R19 vs 255/45R20-0.01%
- 255/50R19 vs 255/55R18+0.01%
- 255/50R19 vs 255/45R19-3.46%
- 255/50R19 vs 225/55R19-1.02%
- 255/50R19 vs 275/40R19-4.75%
- 255/50R19 vs 235/50R19-2.71%
- 255/50R19 vs 245/55R19+1.97%
- 255/50R19 vs 255/55R19+3.46%
- 255/50R19 vs 265/50R19+1.36%
Questions
Can I replace 255/50R19 with 235/50R20?
235/50R20 is a safe swap for 255/50R19 by the usual ±3% rule: the diameter differs by +0.73%.
What's the difference between 255/50R19 and 235/50R20?
235/50R20 is 0.21" taller and 20 mm narrower; the sidewall is -0.39". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 235/50R20 fit on 255/50R19 wheels?
No — 255/50R19 needs a 19" wheel and 235/50R20 a 20" wheel. This is a plus/minus-size swap that changes wheels too.