I have the 2013 X5 35 SA with the 275/40-20s and 315/35-20s in the rear. I wanted to stick with run flats, but didn't want skinny tires as I love the look of the 315s, so I went with a squared set of Pirelli Winter Carving 275/40-20 run flat snow tires on Niche M133 black wheels. I haven't received them yet, but will post a pick once they are on.