245/45R17 vs 255/45R17
255/45R17 is a safe swap for 245/45R17 by the usual ±3% rule: the diameter differs by +1.38%.
Speedometer and odometer
With 255/45R17 on a car calibrated for 245/45R17, the speedometer reads 59.2 mph when you're really doing 60, and the odometer under-counts by 1.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.4 mph |
| 45 mph | 45.6 mph |
| 60 mph | 60.8 mph |
| 70 mph | 71.0 mph |
| 80 mph | 81.1 mph |
Other sizes close to 245/45R17
- 245/45R17 vs 225/45R17-2.76%
- 245/45R17 vs 245/40R18+0.14%
- 245/45R17 vs 225/50R17+0.69%
- 245/45R17 vs 225/55R17+4.14%
- 245/45R17 vs 215/45R17-4.14%
- 245/45R17 vs 205/50R17-2.38%
- 245/45R17 vs 215/55R17+2.45%
- 245/45R17 vs 215/50R17-0.84%
- 245/45R17 vs 235/45R17-1.38%
- 245/45R17 vs 205/60R16+0.02%
- 245/45R17 vs 245/40R17-3.76%
- 245/45R17 vs 275/35R18-0.40%
Questions
Can I replace 245/45R17 with 255/45R17?
255/45R17 is a safe swap for 245/45R17 by the usual ±3% rule: the diameter differs by +1.38%.
What's the difference between 245/45R17 and 255/45R17?
255/45R17 is 0.35" taller and 10 mm wider; the sidewall is +0.18". At an indicated 60 mph you'd actually be doing 60.8 mph.
Will 255/45R17 fit on 245/45R17 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.