I would stick with 15" wheels. I only say that because your tire selection with 16" wheels is very limited. I run the factory 16" Moab wheels on my Rubicon, and I'm fine with it, but only because I don't need the tire selection that some guys need who do a lot of serious off-roading. When I did look for tires though, I noticed that there's far less mud terrain and other aggressive tires for 16" wheels than there is for 15" wheels. They're also more expensive as well!
However, Goodyear makes the Duratrac (my favorite tire) for 16" wheels, so I have no issues there at all. I'm simply saying that if you want a huge variety of tires and sizes to choose from, 15" wheels are generally a better choice.
31" or 32" tires will fit, and you shouldn't have any issues with a 10.5" wide tire, even with factory backspacing. The idea back spacing is usually around 3.75" to 4" though if you have a choice.
