255/70R18 vs 33x12.50R18
33x12.50R18 is a safe swap for 255/70R18 by the usual ±3% rule: the diameter differs by +2.95%.
Side by side
| 255/70R18 | 33x12.50R18 | Difference | |
|---|---|---|---|
| Overall diameter | 32.06" | 33.00" | +0.94" (+2.95%) |
| Section width | 255 mm | 318 mm | +63 mm |
| Sidewall | 7.03" | 7.50" | +0.47" |
| Rim | 18" | 18" | same |
| Circumference | 100.7" | 103.7" | +3.0" |
| Revs per mile | 629 | 611 | -18 |
| Ride height | — | — | +0.47" |
| Speedometer reads 60 mph | 60.0 | 61.8 | +1.8 mph |
Speedometer and odometer
With 33x12.50R18 on a car calibrated for 255/70R18, the speedometer reads 58.3 mph when you're really doing 60, and the odometer under-counts by 2.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.9 mph |
| 45 mph | 46.3 mph |
| 60 mph | 61.8 mph |
| 70 mph | 72.1 mph |
| 80 mph | 82.4 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 285/60R18-1.84%
- 255/70R18 vs 275/70R17+0.32%
- 255/70R18 vs 305/65R18+4.85%
Questions
Can I replace 255/70R18 with 33x12.50R18?
33x12.50R18 is a safe swap for 255/70R18 by the usual ±3% rule: the diameter differs by +2.95%.
What's the difference between 255/70R18 and 33x12.50R18?
33x12.50R18 is 0.94" taller and 63 mm wider; the sidewall is +0.47". At an indicated 60 mph you'd actually be doing 61.8 mph.
Will 33x12.50R18 fit on 255/70R18 wheels?
Both use a 18" rim, so the wheel diameter matches; check the wheel's width range for a 318 mm tire and the fender clearance.