Not what you're looking for and a distance away, but may be of interest if nothing more appropriate turns up, I have a set of Styling 108 18's. I bought them a couple of years ago from BM Autosport in the UK to hold the Z4 up while I had the MV2's refurb'd. They're typically an e85 Z4 wheel so should fit an e46 with no bother. Currently they have some old run flats on them but I'm not sure I'd use them for anything. Thread is OK but they seemed pretty hard when I used them on the Z, but it looks like that won't matter to you. If nothing else turns up, let me know.