Welcome, really like the look of this car. The alloys are the same style as those from an E46 M3, I had a set of 18" previously on my E36. With regards to 18"s and the Eibach springs I had exactly the same set up with no issues at all so it will be fine if you go down this route. I have also recently fitted coilovers to my zed but I am not happy with the rears so may have to put the Eibach springs on the back again unless they settle further and it makes any difference with the adjusters removed.