Bill,
Before I installed my stuff, I was going to go with a 16" wheel. The guys at 4WPPC put together a package for me which consisted of the Skyjacker 5" lift, 16 x 8 589's and 36/12.50/16 Super Swamper TLS Radials. They always recommend this set up for alot of dodges and they dont get any problems. My welds are 15 x 8 with 4.50" of back spacing and my tires are flush with my fenders...well, actually they stick out about an inch or two, which I think it looks really clean. A wheel with 3.50" of back spacing sticks out alot and I dont really like how that looks in my opinion, but many people do like their tires sticking out of their fenders....