There is a tire size calculator
I often refer to and 33x12.5x17 is not a size I can choose. Are you sure that tire size is made?
You are right though, Duratrac 285/70R17 tires are 32.7" in diameter and 11.22" wide and the next size up for the 17" tires are the 315/70R17 tires run 34.36" in diameter and 12.4" wide.
When I get new tires I plan on down sizing the wheels to 16" so I can have more choices. I currently run 305/65R17 ProComp Xtreme MT tires that run 32.61" in diameter and 12" wide. Is that more what you are looking for?