285/60R18 vs 33x12.50R18
33x12.50R18 is outside the ±3% rule as a replacement for 285/60R18: the diameter differs by +4.88%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Side by side
| 285/60R18 | 33x12.50R18 | Difference | |
|---|---|---|---|
| Overall diameter | 31.46" | 33.00" | +1.54" (+4.88%) |
| Section width | 285 mm | 318 mm | +33 mm |
| Sidewall | 6.73" | 7.50" | +0.77" |
| Rim | 18" | 18" | same |
| Circumference | 98.8" | 103.7" | +4.8" |
| Revs per mile | 641 | 611 | -30 |
| Ride height | — | — | +0.77" |
| Speedometer reads 60 mph | 60.0 | 62.9 | +2.9 mph |
Speedometer and odometer
With 33x12.50R18 on a car calibrated for 285/60R18, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 4.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.5 mph |
| 45 mph | 47.2 mph |
| 60 mph | 62.9 mph |
| 70 mph | 73.4 mph |
| 80 mph | 83.9 mph |
Other sizes close to 285/60R18
- 285/60R18 vs 265/70R17+0.45%
- 285/60R18 vs 275/65R18+1.94%
- 285/60R18 vs 265/60R18-3.00%
- 285/60R18 vs 265/65R18+0.31%
- 285/60R18 vs 265/70R18+3.63%
- 285/60R18 vs 235/65R18-4.57%
- 285/60R18 vs 245/75R17+0.01%
- 285/60R18 vs 255/70R18+1.88%
- 285/60R18 vs 255/65R18-1.31%
- 285/60R18 vs 285/65R18+3.57%
- 285/60R18 vs 255/60R18-4.50%
- 285/60R18 vs 275/60R18-1.50%
Questions
Can I replace 285/60R18 with 33x12.50R18?
33x12.50R18 is outside the ±3% rule as a replacement for 285/60R18: the diameter differs by +4.88%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 285/60R18 and 33x12.50R18?
33x12.50R18 is 1.54" taller and 33 mm wider; the sidewall is +0.77". At an indicated 60 mph you'd actually be doing 62.9 mph.
Will 33x12.50R18 fit on 285/60R18 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.