I think you need to be a bit more educated.
One is metric, on is standard. When one is talking about 33s, a lot of the time they are only talking about the height of the tire and making no reference to the width. You can have a 275 60 20 that is a 33 but only 11" wide and a 305 55 20 that is a 33 but almost 12.5" wide. 305 is the width of the tire in mm. The 55 is the aspect ratio.
Do some googling its really all quite simple.
---------- Post added at 04:30 PM ---------- Previous post was at 04:27 PM ----------
I have 6" of lift on 33s, but I have 20x12" wheels on 33 12.50 20 Toyo mts. A common tire size on f250s is the 275 60 20 which is almost 33" tall but because it has a narrower wheel at 8.5" wide you run a less wide tire for correct fitment and to get proper wear and traction from the tire.
