With a completely stock suspension I think the best size is a 275/65/20 which is just one size taller than stock. No worries about any type of rubbing, fills the fender well up nicely, and that size is only available as a "LT" or E-rated tire so it's tough. What brand or specific tire I guess depends on how rough you want to go....as in all-terrain or mud tire? Cooper Zeon LTZ, Nitto Terra Grapplers, and Toyo Open Country A/T seem to be very popular but I'm sure you could find several great A/T tires in that size. Nitto Trail Grapplers and Toyo Open Country M/T seem to be two of the best mud tires on the market but I don't think the Trail Grapplers are available in 275/65/20.
06-08 chrome clads w/33" Cooper Discoverer H/T Plus, Mopar tailgate spoiler, debadged door trim & tailgate emblems, 13" antenna, LED dome & maps, Magnaflow 22" SI/DO, 18% tint, "HEMI" hood spears, VHT tinted tails & third brake light, Lamin-x optic blue fogs, leveled w/McGaughys 2" drop shackles.