If you are going from 15's to 17's pick your tires wisely. You are about to enter the world of trammeling, where your car will want to follow seams, rain grooves and gets way twitchy on un even or rutted pavement. Tires make a large difference on how bad it is, suspension components do the rest of the job. I have had good luck with Sumitomo HTR Z II tires in 235/40/17 and very very bad luck with Dunlop D40 in a 215/45/17 car was almost undriveable. That is only two, there are many others so check the archives and also the reports on Tire rack. Heavy research here will save you a big headache. Heavier sways help to (350 in parts, easy DYS job), mostly for uneven pavement trammeling. M3's, which come stock with 17's, have different control arm bushings and radically different strut tower bearings which alter the E36 geometry to stop the problem ($400 in parts alone for the conversion). Just wanted you to know what you are getting into.