i was just going to tell you waht fairgentleman told you.
get the fattest 17 bmw rim, as you know it will fit your application and give you tire options
-dont get r comps if you have never raced before, or have limited experience as this will help you learn the limits and characteristics of your application.
another rim choice could be the Kosei K1, cheap, light, strong(tho idk if they make them to fit your 3 series)
–or even another would be ssr comps, light, prolly not as expensive as the bbs and will def. fit/run the sizes you want and give you the reliability you need.
as for tires, your running street tires anyway, go to tirerack and get the optimal street tire for your needs(durability/grip/size/expense)