275/65R18 vs 33x12.50R18
33x12.50R18 is a safe swap for 275/65R18 by the usual ±3% rule: the diameter differs by +2.88%.
Side by side
| 275/65R18 | 33x12.50R18 | Difference | |
|---|---|---|---|
| Overall diameter | 32.07" | 33.00" | +0.93" (+2.88%) |
| Section width | 275 mm | 318 mm | +43 mm |
| Sidewall | 7.04" | 7.50" | +0.46" |
| Rim | 18" | 18" | same |
| Circumference | 100.8" | 103.7" | +2.9" |
| Revs per mile | 629 | 611 | -18 |
| Ride height | — | — | +0.46" |
| Speedometer reads 60 mph | 60.0 | 61.7 | +1.7 mph |
Speedometer and odometer
With 33x12.50R18 on a car calibrated for 275/65R18, 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 | 61.7 mph |
| 70 mph | 72.0 mph |
| 80 mph | 82.3 mph |
Other sizes close to 275/65R18
- 275/65R18 vs 265/60R18-4.85%
- 275/65R18 vs 275/70R18+3.38%
- 275/65R18 vs 265/65R18-1.60%
- 275/65R18 vs 265/70R18+1.66%
- 275/65R18 vs 235/80R17-0.85%
- 275/65R18 vs 255/70R18-0.06%
- 275/65R18 vs 255/65R18-3.19%
- 275/65R18 vs 285/65R18+1.60%
- 275/65R18 vs 255/75R17-0.05%
- 275/65R18 vs 285/60R18-1.90%
- 275/65R18 vs 275/70R17+0.26%
- 275/65R18 vs 305/65R18+4.79%
Questions
Can I replace 275/65R18 with 33x12.50R18?
33x12.50R18 is a safe swap for 275/65R18 by the usual ±3% rule: the diameter differs by +2.88%.
What's the difference between 275/65R18 and 33x12.50R18?
33x12.50R18 is 0.93" taller and 43 mm wider; the sidewall is +0.46". At an indicated 60 mph you'd actually be doing 61.7 mph.
Will 33x12.50R18 fit on 275/65R18 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.