275/55R20 vs 33x12.50R20: full comparison
| Measurement | 275/55R20 | 33x12.50R20 | Difference |
|---|---|---|---|
| Diameter | 31.91 in | 33.00 in | +1.09 in+3.4% |
| Section width | 10.83 in | 12.50 in | +1.67 in+15.5% |
| Sidewall height | 5.95 in | 6.50 in | +0.55 in+9.2% |
| Circumference | 100.25 in | 103.67 in | +3.43 in+3.4% |
| Revs per mile | 632 | 611 | −21−3.3% |
Speedometer: indicated vs actual speed
With 33x12.50R20 fitted where 275/55R20 was the stock/calibrated size:
| Speedometer shows | Actual speed | Difference |
|---|---|---|
| 20 mph | 20.7 mph | +0.7 mph |
| 30 mph | 31.0 mph | +1.0 mph |
| 40 mph | 41.4 mph | +1.4 mph |
| 50 mph | 51.7 mph | +1.7 mph |
| 55 mph | 56.9 mph | +1.9 mph |
| 60 mph | 62.1 mph | +2.1 mph |
| 65 mph | 67.2 mph | +2.2 mph |
| 70 mph | 72.4 mph | +2.4 mph |
| 75 mph | 77.6 mph | +2.6 mph |
| 80 mph | 82.7 mph | +2.7 mph |
Recalculate for a gear ratio change too →
Will 33x12.50R20 fit where 275/55R20 was?
At +3.4%, 33x12.50R20 is enough larger than 275/55R20 that it commonly needs some accommodation -- trimming plastic liners/fender edges, a spacer, or a leveling kit on trucks/SUVs going bigger. Check clearance at full steering lock and full suspension compression before buying.
Related tire size comparisons
- 275/55R20 vs 275/60R20
- 275/55R20 vs 275/65R20
- 275/55R20 vs 285/55R20
- 265/60R20 vs 275/55R20
- 275/60R20 vs 33x12.50R20
More tire tools
- Tire size comparison tool: compare any two sizes yourself, including flotation sizes.
- Tire size calculator: full dimensions of one size, plus every equivalent size within 3%.
- Speedometer calculator: true speed after a tire or gear ratio change.
Frequently asked questions
How much bigger is 33x12.50R20 than 275/55R20?
33x12.50R20 is 1.09 in taller in overall diameter (+3.4%) and 1.67 in wider in section width (+15.5%) than 275/55R20.
Will 33x12.50R20 fit in place of 275/55R20?
At +3.4%, 33x12.50R20 is enough larger than 275/55R20 that it commonly needs some accommodation -- trimming plastic liners/fender edges, a spacer, or a leveling kit on trucks/SUVs going bigger. Check clearance at full steering lock and full suspension compression before buying.
Does swapping to 33x12.50R20 affect my speedometer?
With 33x12.50R20 fitted where 275/55R20 was calibrated, an indicated 60 mph is really about 62.1 mph. Beyond the ±3% guideline, plan to recalibrate the speedometer/odometer (with a programmer or at the dealer) for an accurate reading.
Does 33x12.50R20 change the ride height?
Yes -- half the diameter difference shows up at the axle, so 33x12.50R20 changes ride height by about 0.55 in higher compared with 275/55R20.
Can I compare a metric size (like 275/55R20) with a flotation size (like 33x12.50R20)?
Yes -- both are converted to inches and millimeters before comparing, so the diameter, width and speedometer numbers above are directly comparable regardless of which sizing system each tire uses.