I guess I just prefer smallish tyres - the same (but a totally different thing) on my MTB - I love 1.8" rubber, most get massively fat tyres.
30 is VERY low profile indeed. Just not my cup of tea at all.
Cheers for the tyre size education though - clearly a hole in my knowledge.
I think 18s are fine/good on an E9* - I think 19s are a step too far and for once an E90Post "player" agrees with me...
E91 335d SE Touring
Also Land Rover Puma Defender 110 XS station wagon