255/45R17 vs 235/50R17
235/50R17 is a safe swap for 255/45R17 by the usual ±3% rule: the diameter differs by +0.83%.
Speedometer and odometer
With 235/50R17 on a car calibrated for 255/45R17, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.7 mph |
Other sizes close to 255/45R17
- 255/45R17 vs 225/45R17-4.08%
- 255/45R17 vs 225/45R18-0.24%
- 255/45R17 vs 225/50R17-0.68%
- 255/45R17 vs 225/55R17+2.72%
- 255/45R17 vs 235/55R17+4.39%
- 255/45R17 vs 205/50R17-3.70%
- 255/45R17 vs 215/55R17+1.06%
- 255/45R17 vs 215/50R17-2.19%
- 255/45R17 vs 235/45R17-2.72%
- 255/45R17 vs 245/45R17-1.36%
- 255/45R17 vs 215/60R16+0.47%
- 255/45R17 vs 255/40R18-0.02%
Questions
Can I replace 255/45R17 with 235/50R17?
235/50R17 is a safe swap for 255/45R17 by the usual ±3% rule: the diameter differs by +0.83%.
What's the difference between 255/45R17 and 235/50R17?
235/50R17 is 0.22" taller and 20 mm narrower; the sidewall is +0.11". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 235/50R17 fit on 255/45R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 235 mm tire and the fender clearance.