The Tire Rack website can give you alot of info on wheel requirements and tire dimensions. I think the 255's will fit 9 inch wheels but the wheel edge will be about as wide as the section width. Don't know if you like that look or not. I like a little bulge. The 275's will give you that. To me the 275's are perfect on 9's. I have had 3 differant sets in that size, Goodyear F1 GS's, Nittos, and now BFG's, and none have rubbed.
I think I'm going to get 265's for up front and 285's for the back. If I want to save money in the long run, I'm just gonna get 265's all around so that I can rotate them. Not sure yet