You can get any size tire to fit any size wheel, within reason, hell I have a 13.5 wide tire mounted on a 6.5" wide wheel as a spare, and 15.50s mounted on 10" wide wheel with no issues.
The only issue you will run into is the center tread will wear slightly faster than the outside tread, with that said, I ran a 285/75R16 (Like many do) on my stock 16x6.5" wheels. After nearly 50k miles on the BFG MTs the center tread was a little more worn than the outer, roughly 1/8" deep in the center, and 1/4" deep on the outer. But who can complain about getting 50k out of mud tires. Others have worse results, but the key is watching tire pressures. Lower pressures will even out the tread, but will hurt fuel economy, and can actually wear the entire tire faster due to heat. Higher pressure will "crown" the tread, wear the center faster, and get better fuel economy. It's all about finding a happy medium.
33x12.5 will fit onto a x7, but I think you would be happier with a 32x11.5 with your setup, both looks and performance wise.