after reading many many 18s v. 19s thraed this is the bottom line:
19s look better and fit the car better.
18s ride and handle better.
Which do you want? "looks" or "performance" ?
(Yes, you can get both out of a wheel of either size - but it boils down to that: looks or performance... simple as that)
2008 328i E90 Jet Black:6MT:Premium:Sport:Walnut/Black interior:Xenon:MTEC V3 AEs:19" Beyern Mesh:35% Tint:Blacklines