Niko, I've provided links below to the winter tires/wheels combination Tirerack has available for the E90. In my experience, you simply can't go wrong with the Bridgestone Blizzak tires. I'm sure others will agree.
Winter Tires/Wheels for 325i (base model)
Winter Tires/Wheels for 325i (w/ sports package)
Winter Tires/Wheels for 330i (base model)
Winter Tires/Wheels for 330i (w/ sports package)