1985 z31 wheel fitment
 

I was going to order the XXR 527 17's and I was wondering if I needed spacres for them to be flush. For now I have the car lowered on the stock rims like so.
http://i43.tinypic.com/353bh3n.jpg
Please let me know! I'd appreciate it.

Your best bet would be to read up on wheel offsets, how they work and what they are on both the stock wheels and the wheels you want to put on the car. Then you'll be able to answer your own question.