Hey man, for what it's worth i've been doing quite a bit of research on wheels and tires and what'll fit, what wont. I think I'm gonna end up going with a 22x9.5 rockstar, it's an 18mm offset, where stock is 20mm.
As for tire, I'm gonna go with the nitto trail grappler 305/45/22
exact dimensions on the tire are 32.68" diameter (basically 33's) 11.89 wide. I'll be getting my truck leveled before I put them on, but I don't expect any clearance issues.
I love nitto's site because you can see the exact dimensions of the tires. If youre gonna go 20x10 you'll have a lot more options for tire than i will with the 22, but the cool thing about the terra grapplers is that you can get a heavy load rating!
http://www.rimsntires.com/specs.jsp
here's a GREAT tool for comparing tire sizes, with wheel sizes etc. I recommend setting your vehicle and selecting your stock size, go outside and turn your truck to full lock and see how much room your working with, need a bit of room to allow for bumps and such at full lock, but you'll get a general idea of what you can fit under there.
hope i've been some help, good luck!