235/55R20 vs 255/55R20
255/55R20 is a safe swap for 235/55R20 by the usual ±3% rule: the diameter differs by +2.87%.
Speedometer and odometer
With 255/55R20 on a car calibrated for 235/55R20, the speedometer reads 58.3 mph when you're really doing 60, and the odometer under-counts by 2.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.9 mph |
| 45 mph | 46.3 mph |
| 60 mph | 61.7 mph |
| 70 mph | 72.0 mph |
| 80 mph | 82.3 mph |
Other sizes close to 235/55R20
- 235/55R20 vs 245/45R20-4.96%
- 235/55R20 vs 255/45R20-3.78%
- 235/55R20 vs 255/50R20-0.46%
- 235/55R20 vs 265/50R20+0.85%
- 235/55R20 vs 245/50R20-1.76%
- 235/55R20 vs 275/45R20-1.44%
- 235/55R20 vs 265/45R20-2.61%
- 235/55R20 vs 255/55R19-0.44%
- 235/55R20 vs 315/35R20-4.96%
- 235/55R20 vs 275/50R20+2.15%
- 235/55R20 vs 295/40R20-2.94%
- 235/55R20 vs 285/50R20+3.46%
Questions
Can I replace 235/55R20 with 255/55R20?
255/55R20 is a safe swap for 235/55R20 by the usual ±3% rule: the diameter differs by +2.87%.
What's the difference between 235/55R20 and 255/55R20?
255/55R20 is 0.87" taller and 20 mm wider; the sidewall is +0.43". At an indicated 60 mph you'd actually be doing 61.7 mph.
Will 255/55R20 fit on 235/55R20 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.