Yeah I believe they are 9" wide. Which will easily fit both. And no they wont look weird. Alot of people, including myself run a staggered setup. I have 245s up front, and 285s in the rear.
The benefit is that you will get more grip in the rear, and have less weight in the front. If you plan of auto crossing the car, i would recommend going with a wider tire in the front. Otherwise a staggered setup is a good option, other than the fact you will not be able to rotate your tires.
2014 Mustang GT Base MT82 -Stock 3.73s, Roush axleback, Steeda 93R tune, Steeda Hi-flow X-pipe, 19" Charcoal AMR's, smoked front and rear side markers, 20% tint, quarter window louvers, Steeda Ultralite springs, Koni Str.t shocks/struts, MM camber plates, J&M adjustable panhard bar, BMR LCAs and relo brackets, Barton shifter and 2-post bracket, Black Modern Billet Grilles