33x12.50R20 vs 285/65R20
285/65R20 is outside the ±3% rule as a replacement for 33x12.50R20: the diameter differs by +4.81%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Side by side
| 33x12.50R20 | 285/65R20 | Difference | |
|---|---|---|---|
| Overall diameter | 33.00" | 34.59" | +1.59" (+4.81%) |
| Section width | 318 mm | 285 mm | -33 mm |
| Sidewall | 6.50" | 7.29" | +0.79" |
| Rim | 20" | 20" | same |
| Circumference | 103.7" | 108.7" | +5.0" |
| Revs per mile | 611 | 583 | -28 |
| Ride height | — | — | +0.79" |
| Speedometer reads 60 mph | 60.0 | 62.9 | +2.9 mph |
Speedometer and odometer
With 285/65R20 on a car calibrated for 33x12.50R20, the speedometer reads 57.2 mph when you're really doing 60, and the odometer under-counts by 4.8%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.4 mph |
| 45 mph | 47.2 mph |
| 60 mph | 62.9 mph |
| 70 mph | 73.4 mph |
| 80 mph | 83.8 mph |
Other sizes close to 33x12.50R20
- 33x12.50R20 vs 275/55R20-3.30%
- 33x12.50R20 vs 275/60R20-0.02%
- 33x12.50R20 vs 275/65R20+3.26%
- 33x12.50R20 vs 265/60R20-1.46%
- 33x12.50R20 vs 305/55R20+0.63%
- 33x12.50R20 vs 285/55R20-1.99%
- 33x12.50R20 vs 285/60R20+1.41%
- 33x12.50R20 vs 295/60R20+2.84%
- 33x12.50R20 vs 295/55R20-0.68%
- 33x12.50R20 vs 245/60R20-4.32%
- 33x12.50R20 vs 305/50R20-3.01%
- 33x12.50R20 vs 255/60R20-2.89%
Questions
Can I replace 33x12.50R20 with 285/65R20?
285/65R20 is outside the ±3% rule as a replacement for 33x12.50R20: the diameter differs by +4.81%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 33x12.50R20 and 285/65R20?
285/65R20 is 1.59" taller and 33 mm narrower; the sidewall is +0.79". At an indicated 60 mph you'd actually be doing 62.9 mph.
Will 285/65R20 fit on 33x12.50R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 285 mm tire and the fender clearance.