235/50R20 vs 255/50R20
255/50R20 is a safe swap for 235/50R20 by the usual ±3% rule: the diameter differs by +2.69%.
Speedometer and odometer
With 255/50R20 on a car calibrated for 235/50R20, the speedometer reads 58.4 mph when you're really doing 60, and the odometer under-counts by 2.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.8 mph |
| 45 mph | 46.2 mph |
| 60 mph | 61.6 mph |
| 70 mph | 71.9 mph |
| 80 mph | 82.2 mph |
Other sizes close to 235/50R20
- 235/50R20 vs 235/55R19-0.26%
- 235/50R20 vs 245/45R20-1.95%
- 235/50R20 vs 255/45R20-0.74%
- 235/50R20 vs 255/50R19-0.73%
- 235/50R20 vs 275/40R20-2.02%
- 235/50R20 vs 265/50R20+4.04%
- 235/50R20 vs 245/50R20+1.35%
- 235/50R20 vs 275/45R20+1.68%
- 235/50R20 vs 235/55R20+3.16%
- 235/50R20 vs 255/40R20-4.17%
- 235/50R20 vs 265/45R20+0.47%
- 235/50R20 vs 285/35R20-4.78%
Questions
Can I replace 235/50R20 with 255/50R20?
255/50R20 is a safe swap for 235/50R20 by the usual ±3% rule: the diameter differs by +2.69%.
What's the difference between 235/50R20 and 255/50R20?
255/50R20 is 0.79" taller and 20 mm wider; the sidewall is +0.39". At an indicated 60 mph you'd actually be doing 61.6 mph.
Will 255/50R20 fit on 235/50R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.