IIRC when guys run 32x11.5 (275/55R20 = 32x11) they need at least a 3" lift and still rub some. Did you check out the lifted wheel/tire fitment chart?
Correct me if I'm wrong but aren't your stock wheels 7" wide?Online Wheel and Tyre Fitment Calculator. Offset, Tyre Stretch and Speedo Error | Will They Fit
That's what the calculator says
Yeah he had 9" in the calculator.Factory wheel specs are 17x7 with an offset of 33.
https://www.wheel-size.com/size/chevrolet/colorado/2009/#trim-37-z71-usdm