255/80R17 vs 325/60R18
325/60R18 is a safe swap for 255/80R17 by the usual ±3% rule: the diameter differs by +0.88%.
Speedometer and odometer
With 325/60R18 on a car calibrated for 255/80R17, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.3 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.7 mph |
Other sizes close to 255/80R17
- 255/80R17 vs 265/70R17-4.41%
- 255/80R17 vs 275/70R18+0.29%
- 255/80R17 vs 285/70R17-1.07%
- 255/80R17 vs 245/75R17-4.82%
- 255/80R17 vs 235/80R17-3.81%
- 255/80R17 vs 285/75R16-0.70%
- 255/80R17 vs 315/70R17+3.93%
- 255/80R17 vs 255/75R17-3.04%
- 255/80R17 vs 295/70R17+0.60%
- 255/80R17 vs 33x12.50R18-0.19%
- 255/80R17 vs 305/70R16-0.76%
- 255/80R17 vs 285/75R17+2.32%
Questions
Can I replace 255/80R17 with 325/60R18?
325/60R18 is a safe swap for 255/80R17 by the usual ±3% rule: the diameter differs by +0.88%.
What's the difference between 255/80R17 and 325/60R18?
325/60R18 is 0.29" taller and 70 mm wider; the sidewall is -0.35". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 325/60R18 fit on 255/80R17 wheels?
No — 255/80R17 needs a 17" wheel and 325/60R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.