Hey whats up! Always happy to help. Well wheel size is all about preference and not fitment. I personally like the look of 16s on an e30 even though I'm going to try 17s later this year. I'm currently running 16x8 et13(2" lip) in the front and 16x9 et13(2.5" Lip) in the rear. Fitment upfront is perfect with no rubbing, rears required me to roll the fenders though but overall fitment is pretty spot on. As far as fitment is concerned, I would stay between +12 and +20 offsets. Anything less than +10 and I believe it'll start to poke. I hope thats a least able to get you in the right direction. Feel free to ask any more questions.
