....on a 2008 550i with sport package. BMW dealers say that BMW does NOT reccommend 18".

 

17" is better. Cuts through snow better.

Always go for the smallest possible diameter that will clear your brakes.

See my post from yesterday - http://forums.e60.net/index.php?showtopic=48424

 

I'm sure that 17s are better than 18s and that 16s are better than 17s . . . I think that you've just got to pick your poison. I've run 18s on both of my E60s. It ain't no Jeep, but I've never got stuck either.

btw, I run 18s because they just look better than the 17s or the 16s.

 

I went with 18's. I do agree that 17 may be better but felt the change from 19's to 17's would be to difficult of an adjustment given the sport package. I just ordered them last week and not on the car as of yet so no assessment of performance.

 

I wondered about that as well but spoke with experts at Bridgestone and BMW and they assured me 17" would be fine with the sport suspension. My first few days in driving indicates that they were correct.

 

I use 17" for winter as well. Aside from the great traction, I have an additional cushion against any pothole damage. The car drives fine and you get used to the way it looks after a couple days...

 

I use 18" and it's evident that the surface must be pretty smooth in order to have decent ride. Actually, my winter-GY has a harsher ride than my 19" Summer-Conti...

 

I have the 17" with Blizzak WS50 and handling is fine till I hit 80MPH and get a bit of a wandering feeling but still in control.

 

Luckily I don't get that on the LM25s.

 

However, I am very happy and satisfied with their winter (snow/ice) handling abilities.