I have 16.5" x 9.75" Centerline wheels running 33 X 12.5" BFG Tires ... an exact 2:1 ratio ... maximizing the "wheel look" while maintaining a decent level of sidewall.
My philosophy is to maintain a (minimum) 2:1 Tire Diameter to Wheel Diameter. In my opinion, anything less than this ratio gets into the "bling" category and is no longer a real truck.
On clearance, my wheels have a 4.25" backspace and are right on the hairy edge of rubbing the radius arms on full-lock. Also, I have a 2.5" suspension lift, and a 1" body lift.