245/40R17 vs 225/45R17
225/45R17 is a safe swap for 245/40R17 by the usual ±3% rule: the diameter differs by +1.04%.
Speedometer and odometer
With 225/45R17 on a car calibrated for 245/40R17, the speedometer reads 59.4 mph when you're really doing 60, and the odometer under-counts by 1.0%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.3 mph |
| 45 mph | 45.5 mph |
| 60 mph | 60.6 mph |
| 70 mph | 70.7 mph |
| 80 mph | 80.8 mph |
Other sizes close to 245/40R17
- 245/40R17 vs 225/50R17+4.62%
- 245/40R17 vs 205/55R16+0.65%
- 245/40R17 vs 215/45R17-0.40%
- 245/40R17 vs 205/50R17+1.43%
- 245/40R17 vs 215/50R17+3.03%
- 245/40R17 vs 235/45R17+2.47%
- 245/40R17 vs 245/45R17+3.90%
- 245/40R17 vs 205/45R17-1.83%
- 245/40R17 vs 255/40R17+1.27%
- 245/40R17 vs 245/35R18+0.14%
- 245/40R17 vs 225/50R16+0.57%
- 245/40R17 vs 205/55R17+4.70%
Questions
Can I replace 245/40R17 with 225/45R17?
225/45R17 is a safe swap for 245/40R17 by the usual ±3% rule: the diameter differs by +1.04%.
What's the difference between 245/40R17 and 225/45R17?
225/45R17 is 0.26" taller and 20 mm narrower; the sidewall is +0.13". At an indicated 60 mph you'd actually be doing 60.6 mph.
Will 225/45R17 fit on 245/40R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 225 mm tire and the fender clearance.