215/50R17 vs 215/45R18
215/45R18 is a safe swap for 215/50R17 by the usual ±3% rule: the diameter differs by +0.60%.
Speedometer and odometer
With 215/45R18 on a car calibrated for 215/50R17, the speedometer reads 59.6 mph when you're really doing 60, and the odometer under-counts by 0.6%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.2 mph |
| 45 mph | 45.3 mph |
| 60 mph | 60.4 mph |
| 70 mph | 70.4 mph |
| 80 mph | 80.5 mph |
Other sizes close to 215/50R17
- 215/50R17 vs 225/45R17-1.93%
- 215/50R17 vs 245/40R18+0.99%
- 215/50R17 vs 225/50R17+1.55%
- 215/50R17 vs 215/45R17-3.32%
- 215/50R17 vs 205/50R17-1.55%
- 215/50R17 vs 215/55R17+3.32%
- 215/50R17 vs 235/40R18-0.25%
- 215/50R17 vs 235/45R17-0.54%
- 215/50R17 vs 245/45R17+0.85%
- 215/50R17 vs 215/55R16-0.60%
- 215/50R17 vs 205/60R16+0.87%
- 215/50R17 vs 245/40R17-2.94%
Questions
Can I replace 215/50R17 with 215/45R18?
215/45R18 is a safe swap for 215/50R17 by the usual ±3% rule: the diameter differs by +0.60%.
What's the difference between 215/50R17 and 215/45R18?
215/45R18 is 0.15" taller and 0 mm wider; the sidewall is -0.42". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 215/45R18 fit on 215/50R17 wheels?
No — 215/50R17 needs a 17" wheel and 215/45R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.