From what I can see, it looks like everyone is running rims with widths between 7" to 10". I've got a set of 12" wide Welds that I'd like to use, but before I put them on, I'd like to know if anyone else has 12"s, and have they had any problems?

First off welcome to the most informational site on the web. I currently am running 20x11 wheels on me truck. On every other truck which were all chevy/gmc I ran 12" wheels with little backspacing half of the tire stuck out. I like the look but be prepared to do a lot of repairs on the front end. You will also need to put a lift if you wan't to run at least 33" tires,depending on backspacing. Hopefully that helps.