to keep things simple, what works on a 14 or 15" wheel as far as offset will work the same on a 17. if you're running stock chrylser 15x7's with 4.25" backspace (1/4"+ offset), then the same size rim with a tire the same overall width and height should work (i.e. if there is a 215/60R15 on the front now on that 15x7 with 4.25" offset, that is 8.5" wide and 25.2" tall, then a 215/50R17 (8.5" wide, 25.5" tall) should fit on a 17x7 with 4.25" offset....on the front, you'll likely need to keep the outer face of the wheel/tire in the same spot to not have fender clearance issues, so if you want to go to an 8" rim, you'd likely need to go from the standard +1/4" offset to +30-32mm (basically all of the extra rim width is pushed to the inside), which is approx. 5.75" backspace. rear is really going to depend on your axle. met a guy with a '73 dart sport and a stock 8.25" rear. to get the tires centered in the wheelwell, he needed custom 15x7's with 3" backspace (so that would be the same as -1" offset)....for me, these wheels kind of speak to me....
