[larelol]

I recently bought a '08 335xi E92 and with that came original 17" summer wheels which I want to change into 18" or 19". The car has the normal factory chassis. The sticker on the door claims front 225/40/18 and 255/35/18 for the back to be the size for 18".

Two issues:
I'm worried about the ride height - the looks. Will 18" look better or 19"? I've searched this forum and some claim that actually 18" will fit more nicely with the default chassis of 335xi's?
I'm not too keen into changing the chassis as I live in Sweden and for the winter the current height is practically required. (I could go for KW coilovers and be able to change the height)

Secondly, what is the best wheel size? Bmw is apparently OK even with the x-Drive to put wider back tyres, yet I've read that people with even setup on all 4 wheels say that understeer is eliminated, car will run more nice and so on.

Please advise

here's the pic with the current BMW original 17" studded winter tyres on (which I plan on keeping):
http://img822.imageshack.us/f/img09641j.jpg/