255/70R18 vs 275/70R17
275/70R17 is a safe swap for 255/70R18 by the usual ±3% rule: the diameter differs by +0.32%.
Speedometer and odometer
With 275/70R17 on a car calibrated for 255/70R18, the speedometer reads 59.8 mph when you're really doing 60, and the odometer under-counts by 0.3%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.1 mph |
| 45 mph | 45.1 mph |
| 60 mph | 60.2 mph |
| 70 mph | 70.2 mph |
| 80 mph | 80.3 mph |
Other sizes close to 255/70R18
- 255/70R18 vs 275/65R18+0.06%
- 255/70R18 vs 265/60R18-4.79%
- 255/70R18 vs 275/70R18+3.44%
- 255/70R18 vs 265/65R18-1.54%
- 255/70R18 vs 265/70R18+1.72%
- 255/70R18 vs 235/80R17-0.79%
- 255/70R18 vs 255/65R18-3.13%
- 255/70R18 vs 285/65R18+1.66%
- 255/70R18 vs 255/75R17+0.01%
- 255/70R18 vs 33x12.50R18+2.95%
- 255/70R18 vs 285/60R18-1.84%
- 255/70R18 vs 305/65R18+4.85%
Questions
Can I replace 255/70R18 with 275/70R17?
275/70R17 is a safe swap for 255/70R18 by the usual ±3% rule: the diameter differs by +0.32%.
What's the difference between 255/70R18 and 275/70R17?
275/70R17 is 0.10" taller and 20 mm wider; the sidewall is +0.55". At an indicated 60 mph you'd actually be doing 60.2 mph.
Will 275/70R17 fit on 255/70R18 wheels?
No — 255/70R18 needs a 18" wheel and 275/70R17 a 17" wheel. This is a plus/minus-size swap that changes wheels too.