I am running a 20x9 on mine... Sorry, I haven't been around long enough to know your truck, but I do have a B2600i 4x4 and at the stock height they were rubbing just the slightest bit at the mud flap, but I took a rubber mallet to it and it doesn't rub anymore. =)
They do stick out about 1.5" but I have an offset of +29... I have pictures in my build thread... Take a look, I am at work, so I can't repost them in this thread (No access to photobucket).
I am running 305/50s on them and that could be the main reason they were rubbing.
Hope this helps.