215/65R17 vs 235/55R18
235/55R18 is a safe swap for 215/65R17 by the usual ±3% rule: the diameter differs by +0.62%.
Speedometer and odometer
With 235/55R18 on a car calibrated for 215/65R17, 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 215/65R17
- 215/65R17 vs 225/55R17-4.50%
- 215/65R17 vs 225/65R17+1.83%
- 215/65R17 vs 235/65R17+3.66%
- 215/65R17 vs 235/55R17-2.95%
- 215/65R17 vs 225/60R17-1.34%
- 215/65R17 vs 225/55R18-0.93%
- 215/65R17 vs 235/60R17+0.35%
- 215/65R17 vs 215/70R16-0.55%
- 215/65R17 vs 215/60R17-3.02%
- 215/65R17 vs 235/65R16+0.08%
- 215/65R17 vs 245/50R17-4.85%
- 215/65R17 vs 255/60R17+3.73%
Questions
Can I replace 215/65R17 with 235/55R18?
235/55R18 is a safe swap for 215/65R17 by the usual ±3% rule: the diameter differs by +0.62%.
What's the difference between 215/65R17 and 235/55R18?
235/55R18 is 0.17" taller and 20 mm wider; the sidewall is -0.41". At an indicated 60 mph you'd actually be doing 60.4 mph.
Will 235/55R18 fit on 215/65R17 wheels?
No — 215/65R17 needs a 17" wheel and 235/55R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.