Wheel and Tire sizing help/options

Hello all, I just bought a 2007 Tacoma TRD Sport with a 3" lift. While i'm not completley new to trucks, I am having a hard time finding the information i'm looking for. The truck i bought needs new tires and the wheels look pretty crappy up close, so I think i'm going to go with new wheels and tires for it. I'm having a hard time deciding on what sizes to go with.
As far as tires, I am probably going to to with Cooper Discoverer AT3's, but unsure of what size to get. Through some research, I saw that people seem to go with either 265's, 275's or 285's. I do not want to do any trimming and defintley dont want any rubbing, so i think i'll go with the 275's.
For wheels, I was thinking of going with 17x8, but i dont know what backspacing, etc. to get. I saw people going with 4.5" backspacing, which i believe is slightly less that the stock wheels, i'm not sure though.
I am just looking for a nice aggressive look, without the tires extending too far past the fenders (illegal in PA), and without them rubbing anything. Any info anyone can give would be appreciated. thanks...

 

i just saw that i totally put this in the wrong section, sorry about that.