Re: really quickly.
330Guy said:
Well it's entirely possible that I'm very misinformed on this issue, in fact it's probably the case. But, how did you manage to keep your old tires when going from 17" wheels that were 7.5" in the front and 8.5" in the rear to 8" by 9", front and back respectively?? Is there any benefit/disadvantage to this?
Sorry for all the questions, I'm intrigued, what can I say 
-Matt.
No problem Matt. The difference in widths of my wheels vs. the OEM's was not enough to warrant another size tire. I experienced this before on my previous car ('99 328i) when I went from 17x8 OEM's to 17x7.5 M Double-spoke 24 replicas. In both cases I checked with the company I was buying the wheels from that the tires I had would fit.
I suppose when you go to a half-inch wider wheel there may be some small difference in terms of the wheel looking more low-profile, and having more contact with the road - but whatever difference there may be is too small for me to detect. I didn't notice any handling or ride differences between the OEM's and the new setup.
The new wheels do have the illusion of being larger (and having lower profile tires), but I think that effect is mostly caused by the design of the wheel rather than the fact that the sidewall is slightly smaller (though maybe it's a bit of both).