Less than 33" tire...like 32.2" for the conversion.
Just splittin hairs there, however, you can go directly to a 33"x12.5x17 w/o issue on the ORE. Everything else Persuader shared is pretty spot on.
As far as lift, when looking at kits is to ignore the stipulation that "does not work with offroad package". BDS says that from what I remember.
The lift in the ORE is purely in the front springs. They give an additional 2" over a non-ORE 4x4 Ram. So, lift kits will be changing that spring out completely. Well, kits that are with springs as opposed to spacers. Spacers you put on top of the coil spring.
Example, 3" kit using coil springs will only net you a change of 1".
Take out 2" ORE coils and put in 3" kit coils.
Hope that answers the question.