Here's a couple of my 2500 on 20s. The all black set are American Mojave Teflons, which stuck out way too far due to the 4.5" backset and 10" width. I currently have the KMC Backseats in black that have a 9" width and 5.5" backset. The 33" BFG handle great though ride a bit rough, so I'm going to try 35s whenever the tires wear out.
The Mojave teflons stuck out about 3.5 inches -- 20x10 with 4.5" backspacing.
The KMC backseats stick out about 1.5 inches -- 20x9 with 5" backspacing.
The KMCs stick out a bit more than I prefer, but if I ever find some OEM flares, they'll be perfect. The Mojaves looked really ghetto sticking out almost 4 inches, and they'd still stick out another 2" past OEM flares, which is why I ditched 'em. Hope that helps.
Bigredram1, I saw your pictures of your mudder behind your 2500 in your gallery. Wholly cow is that funny how much it dwarfs that 2500 which is not small in the least by itself!! Too funny. That must be quite a site that 2500 with your monster on that gooseneck. Post a pic all hooked up sometime?