255/35R18 vs 275/35R18
275/35R18 is a safe swap for 255/35R18 by the usual ±3% rule: the diameter differs by +2.20%.
Speedometer and odometer
With 275/35R18 on a car calibrated for 255/35R18, the speedometer reads 58.7 mph when you're really doing 60, and the odometer under-counts by 2.2%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.7 mph |
| 45 mph | 46.0 mph |
| 60 mph | 61.3 mph |
| 70 mph | 71.5 mph |
| 80 mph | 81.8 mph |
Other sizes close to 255/35R18
- 255/35R18 vs 225/45R17-0.22%
- 255/35R18 vs 245/40R18+2.75%
- 255/35R18 vs 225/45R18+3.78%
- 255/35R18 vs 225/40R18+0.24%
- 255/35R18 vs 205/50R17+0.17%
- 255/35R18 vs 235/40R18+1.49%
- 255/35R18 vs 255/40R18+4.01%
- 255/35R18 vs 265/35R18+1.10%
- 255/35R18 vs 255/40R17+0.02%
- 255/35R18 vs 215/45R18+2.36%
- 255/35R18 vs 245/35R18-1.10%
- 255/35R18 vs 225/35R19+0.69%
Questions
Can I replace 255/35R18 with 275/35R18?
275/35R18 is a safe swap for 255/35R18 by the usual ±3% rule: the diameter differs by +2.20%.
What's the difference between 255/35R18 and 275/35R18?
275/35R18 is 0.55" taller and 20 mm wider; the sidewall is +0.28". At an indicated 60 mph you'd actually be doing 61.3 mph.
Will 275/35R18 fit on 255/35R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 275 mm tire and the fender clearance.