275/40R17 vs 255/45R17
255/45R17 is a safe swap for 275/40R17 by the usual ±3% rule: the diameter differs by +1.46%.
Speedometer and odometer
With 255/45R17 on a car calibrated for 275/40R17, the speedometer reads 59.1 mph when you're really doing 60, and the odometer under-counts by 1.5%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.4 mph |
| 45 mph | 45.7 mph |
| 60 mph | 60.9 mph |
| 70 mph | 71.0 mph |
| 80 mph | 81.2 mph |
Other sizes close to 275/40R17
- 275/40R17 vs 225/45R17-2.68%
- 275/40R17 vs 245/40R18+0.21%
- 275/40R17 vs 225/50R17+0.77%
- 275/40R17 vs 225/55R17+4.22%
- 275/40R17 vs 215/45R17-4.07%
- 275/40R17 vs 205/50R17-2.30%
- 275/40R17 vs 215/55R17+2.53%
- 275/40R17 vs 215/50R17-0.77%
- 275/40R17 vs 235/45R17-1.30%
- 275/40R17 vs 245/45R17+0.08%
- 275/40R17 vs 205/60R16+0.09%
- 275/40R17 vs 245/40R17-3.68%
Questions
Can I replace 275/40R17 with 255/45R17?
255/45R17 is a safe swap for 275/40R17 by the usual ±3% rule: the diameter differs by +1.46%.
What's the difference between 275/40R17 and 255/45R17?
255/45R17 is 0.37" taller and 20 mm narrower; the sidewall is +0.19". At an indicated 60 mph you'd actually be doing 60.9 mph.
Will 255/45R17 fit on 275/40R17 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.