I've given up trying to run a 305 width tire on my 9" wide wheels. I could never get much tread life out of them. I kept wearing the center out of them, and I was most definitely not over-inflating. I'm currently running a 285/55R20, and they seem to be wearing very well, and are about the same height as the 305/50R20s I had been running before.
I'll get a pic when I can. I have 305/55/20 Toyo AT2s on 20x9 kmc addicts. I have the front valence trimmed a little bit so that isn't an issue. They do however rub in the back of the fenderwell. Need to do some minor trimming so that I dont have to put the bars all the way up. I probably have 1/2-3/4 of an inch of thread still available