235/45R17 vs 255/45R17
255/45R17 is a safe swap for 235/45R17 by the usual ±3% rule: the diameter differs by +2.80%.
Speedometer and odometer
With 255/45R17 on a car calibrated for 235/45R17, the speedometer reads 58.4 mph when you're really doing 60, and the odometer under-counts by 2.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.8 mph |
| 45 mph | 46.3 mph |
| 60 mph | 61.7 mph |
| 70 mph | 72.0 mph |
| 80 mph | 82.2 mph |
Other sizes close to 235/45R17
- 235/45R17 vs 225/45R17-1.40%
- 235/45R17 vs 225/40R18-0.95%
- 235/45R17 vs 225/50R17+2.10%
- 235/45R17 vs 215/45R17-2.80%
- 235/45R17 vs 205/50R17-1.01%
- 235/45R17 vs 215/55R17+3.89%
- 235/45R17 vs 235/40R18+0.30%
- 235/45R17 vs 215/50R17+0.54%
- 235/45R17 vs 245/45R17+1.40%
- 235/45R17 vs 215/55R16-0.06%
- 235/45R17 vs 245/40R17-2.41%
- 235/45R17 vs 205/45R17-4.20%
Questions
Can I replace 235/45R17 with 255/45R17?
255/45R17 is a safe swap for 235/45R17 by the usual ±3% rule: the diameter differs by +2.80%.
What's the difference between 235/45R17 and 255/45R17?
255/45R17 is 0.71" taller and 20 mm wider; the sidewall is +0.35". At an indicated 60 mph you'd actually be doing 61.7 mph.
Will 255/45R17 fit on 235/45R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 255 mm tire and the fender clearance.