205/50r15 is the correct size and is not too big for an e30. Too low doesn't look right to me. Call me old but a drop between the lowest pic above and stock to me is what looks proper. If it's too low it looks broken somehow. Too ricer as well. Actually it really bothers me when I see cars too low and not functional. Some think it looks good, but if you're smashing oil pans and dodging potholes and speed bumps that's just ridiculous. That means you can't drive your car hard! I guess you can park hard though.
BMW 325I E30 Chumpcar Race Car
BMW 540iT M-Sport (New Family Hauler)
BMW 135i Msport Daily/track toy