29in tire would be perfect for 4/6
Of course i would go a little bigger and put a good mini tub in it as i love to fill my fenders as well as possible
i would go with a 30-30.5in tire IMO
My 275/30/24s on my old wheel/tire/drop was perfect
30.5in tire @4.5in of drop with a nice minitub and was perfect
On a side note,i believe im about to drop the truck down to 7in up front ,because it sits much higher with the new tires(285/30/24) than it did with 265/35/22
Going to pull the fenders and just cut out all the fenders and it will get tubs in july when i bag