Alot of it is going to depend on what kind of look you're going for. For largest selection of wheels and tires, I'd suggest a 15" rim, 3 1/2" backspacing. Tire size will depend on whether you want a tall skinny tire, like the OE, or a fatter tire like a more modern truck. Something like a 235/75/15 would be a good size, lots of choices in LT ratings. If you can find a rim you like in a 16, with the same 3 1/2" backspace, you could also stay with the 215/85/16s, although I personally would consider a 245/75/16 for more tire selection.
I'd like to add one more thing, don't run tubes in tubless tires. They are not designed to be run with tubes, even radial tubes (which are intended for tube type radials, not for use in tubeless radials), and will have issues with friction caused by the tube and inner liner rubbing together. I work in the tire business, and have seen many tire failures from this, especially if the vehicle sees any highway use.
