275/55R20 vs 33x12.50R20
33x12.50R20 is outside the ±3% rule as a replacement for 275/55R20: the diameter differs by +3.42%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Side by side
| 275/55R20 | 33x12.50R20 | Difference | |
|---|---|---|---|
| Overall diameter | 31.91" | 33.00" | +1.09" (+3.42%) |
| Section width | 275 mm | 318 mm | +43 mm |
| Sidewall | 5.95" | 6.50" | +0.55" |
| Rim | 20" | 20" | same |
| Circumference | 100.2" | 103.7" | +3.4" |
| Revs per mile | 632 | 611 | -21 |
| Ride height | — | — | +0.55" |
| Speedometer reads 60 mph | 60.0 | 62.1 | +2.1 mph |
Speedometer and odometer
With 33x12.50R20 on a car calibrated for 275/55R20, the speedometer reads 58.0 mph when you're really doing 60, and the odometer under-counts by 3.4%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.0 mph |
| 45 mph | 46.5 mph |
| 60 mph | 62.1 mph |
| 70 mph | 72.4 mph |
| 80 mph | 82.7 mph |
Other sizes close to 275/55R20
- 275/55R20 vs 275/60R20+3.39%
- 275/55R20 vs 265/50R20-4.63%
- 275/55R20 vs 255/55R20-2.71%
- 275/55R20 vs 265/60R20+1.91%
- 275/55R20 vs 305/55R20+4.07%
- 275/55R20 vs 285/55R20+1.36%
- 275/55R20 vs 285/60R20+4.87%
- 275/55R20 vs 275/50R20-3.39%
- 275/55R20 vs 295/55R20+2.71%
- 275/55R20 vs 285/50R20-2.16%
- 275/55R20 vs 245/60R20-1.05%
- 275/55R20 vs 305/50R20+0.31%
Questions
Can I replace 275/55R20 with 33x12.50R20?
33x12.50R20 is outside the ±3% rule as a replacement for 275/55R20: the diameter differs by +3.42%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 275/55R20 and 33x12.50R20?
33x12.50R20 is 1.09" taller and 43 mm wider; the sidewall is +0.55". At an indicated 60 mph you'd actually be doing 62.1 mph.
Will 33x12.50R20 fit on 275/55R20 wheels?
Both use a 20" rim, so the wheel diameter matches; check the wheel's width range for a 318 mm tire and the fender clearance.