I have an e36 318is MSport, with staggered Style 32 Wheels, and I am running 225/45x17 on the front, and 235/45 x17 on the rear, as that what was fitted when I bought the car and they appear to work fine, though I do note that BMW recommend 245/40x17 for the rear on their sticker on the B pillar. I am pretty sure the rear is 8.5” with the front being 7.5”. I chose Goodyear Assurances Triplemax 2s as they worked fine on my 2009 Accord Euro wagon, and they seem to work fine on the 318 as well, and they aren’t too expensive. From memory, the rears were actually cheaper than the fronts as they are were a more common size. Hope that helps!