First of all, welcome to werkz
About the wheels: my gut tells me you will be fine. I mean, the ride will be a litle rougher.
Anyhow, the best place to ask this question is the E46 section, where members with mounds of knowldge on your chassis can give you a definitive answer:
http://www.bimmerwerkz.com/forum/3-series-e46-e90/