285/70R17 vs 33x12.50R18
33x12.50R18 is a safe swap for 285/70R17 by the usual ±3% rule: the diameter differs by +0.89%.
Side by side
| 285/70R17 | 33x12.50R18 | Difference | |
|---|---|---|---|
| Overall diameter | 32.71" | 33.00" | +0.29" (+0.89%) |
| Section width | 285 mm | 318 mm | +33 mm |
| Sidewall | 7.85" | 7.50" | -0.35" |
| Rim | 17" | 18" | +1" |
| Circumference | 102.8" | 103.7" | +0.9" |
| Revs per mile | 617 | 611 | -5 |
| Ride height | — | — | +0.15" |
| Speedometer reads 60 mph | 60.0 | 60.5 | +0.5 mph |
Speedometer and odometer
With 33x12.50R18 on a car calibrated for 285/70R17, the speedometer reads 59.5 mph when you're really doing 60, and the odometer under-counts by 0.9%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 30.3 mph |
| 45 mph | 45.4 mph |
| 60 mph | 60.5 mph |
| 70 mph | 70.6 mph |
| 80 mph | 80.7 mph |
Other sizes close to 285/70R17
- 285/70R17 vs 265/70R17-3.37%
- 285/70R17 vs 245/75R17-3.79%
- 285/70R17 vs 265/70R18-0.31%
- 285/70R17 vs 235/80R17-2.77%
- 285/70R17 vs 285/75R16+0.37%
- 285/70R17 vs 285/65R18-0.37%
- 285/70R17 vs 255/75R17-1.99%
- 285/70R17 vs 295/70R17+1.69%
- 285/70R17 vs 305/70R16+0.31%
- 285/70R17 vs 285/75R17+3.43%
- 285/70R17 vs 33x12.50R17+0.89%
- 285/70R17 vs 275/70R17-1.69%
Questions
Can I replace 285/70R17 with 33x12.50R18?
33x12.50R18 is a safe swap for 285/70R17 by the usual ±3% rule: the diameter differs by +0.89%.
What's the difference between 285/70R17 and 33x12.50R18?
33x12.50R18 is 0.29" taller and 33 mm wider; the sidewall is -0.35". At an indicated 60 mph you'd actually be doing 60.5 mph.
Will 33x12.50R18 fit on 285/70R17 wheels?
No — 285/70R17 needs a 17" wheel and 33x12.50R18 a 18" wheel. This is a plus/minus-size swap that changes wheels too.