215/45R18 vs 225/45R18
225/45R18 is a safe swap for 215/45R18 by the usual ±3% rule: the diameter differs by +1.38%.
Speedometer and odometer
With 225/45R18 on a car calibrated for 215/45R18, 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 215/45R18
- 215/45R18 vs 245/40R18+0.38%
- 215/45R18 vs 225/40R18-2.07%
- 215/45R18 vs 225/50R17+0.94%
- 215/45R18 vs 245/45R18+4.15%
- 215/45R18 vs 235/45R18+2.77%
- 215/45R18 vs 235/40R18-0.85%
- 215/45R18 vs 225/50R18+4.84%
- 215/45R18 vs 215/50R17-0.60%
- 215/45R18 vs 245/45R17+0.25%
- 215/45R18 vs 255/35R18-2.31%
- 215/45R18 vs 255/40R18+1.61%
- 215/45R18 vs 245/35R19+0.52%
Questions
Can I replace 215/45R18 with 225/45R18?
225/45R18 is a safe swap for 215/45R18 by the usual ±3% rule: the diameter differs by +1.38%.
What's the difference between 215/45R18 and 225/45R18?
225/45R18 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 225/45R18 fit on 215/45R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 225 mm tire and the fender clearance.