Hi I have searched for info but can?t find why is 19" wheels recomended over 20" from BMW
Some tuners have 20" and others dont :think:
And why do M5 and B5 have 19" and not 20"
1: Is it lighter and perform and handels better
2: To big for the fenders and could couse rubbing
3: Could it affect comfort
4: Could performance be affected due too slowly acceleration and topspeed :think:

I think mainly comfort :thumbsup:

none, it is just BMW does not recommended.

Hartge, ACS, HAMANN and others offer 20-21" in 20" unless you have the FA 245/30 ZR 20 / RA 285/25 ZR 20 it will not rub, whenever I will finaly have mine the rear and only those have to be rolled, but will be done by specialists you can imagine :D As comfort concerned if you do not wanna fly over roadbumps there is no issue, the comfort and the speed is perfect! :thumbsup:

IMO, 20's are inferior to 19's on a regular 5er in all ways except possibly looks--and that is debateable. 20's are losers from a performance perspective in all ways unless a car is designed for them--acceleration slower, handling worse, feel worse, and braking worse. They also cost more. If I had it to do over, I'd stick with 18's and a higher profile tire than my 19" PS2's for comfort--not that the PS2's are particularly uncomfortable.

the bigger the wheel, the heavier it is

ever notice how race cars don't have big wheels?

I think I will go for 19" becouse the comfort and performance. I cant remember but as znod said breaking and handling perfomance will be affected whith 20"

What's the best tyre size to go for on 18" wheels. I need refinement and comfort. Also dumb question is Michelin Pilot Sport the same as Michelin PS2

except when you rim is 13-14kgs :D

If it is a good quality there is no loss of comfort. It more depend on the roads than on the size of a rim. Acceleration is not worse and traction is even better. :thumbsup: