255/50R20 vs 235/55R20
235/55R20 is a safe swap for 255/50R20 by the usual ±3% rule: the diameter differs by +0.46%.
Speedometer and odometer
With 235/55R20 on a car calibrated for 255/50R20, 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 255/50R20
- 255/50R20 vs 245/45R20-4.52%
- 255/50R20 vs 255/45R20-3.34%
- 255/50R20 vs 275/40R20-4.59%
- 255/50R20 vs 265/50R20+1.31%
- 255/50R20 vs 245/50R20-1.31%
- 255/50R20 vs 275/45R20-0.98%
- 255/50R20 vs 255/55R20+3.34%
- 255/50R20 vs 265/45R20-2.16%
- 255/50R20 vs 255/55R19+0.01%
- 255/50R20 vs 315/35R20-4.52%
- 255/50R20 vs 275/50R20+2.62%
- 255/50R20 vs 295/40R20-2.49%
Questions
Can I replace 255/50R20 with 235/55R20?
235/55R20 is a safe swap for 255/50R20 by the usual ±3% rule: the diameter differs by +0.46%.
What's the difference between 255/50R20 and 235/55R20?
235/55R20 is 0.14" taller and 20 mm narrower; the sidewall is +0.07". At an indicated 60 mph you'd actually be doing 60.3 mph.
Will 235/55R20 fit on 255/50R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 235 mm tire and the fender clearance.