Originally Posted by windwagen
At the risk of getting flamed here, I recommend leaving it alone. Some very picky German engineers chose those sizes for a reason, and it wasn't to reduce costs!
Yes, they chose that because most drivers cannot handle a vehicle that is oversteering. Also, plowing the side into a tree is a lot more dangerous in an extreme situation than hitting something head on and all of the air bags deploy. That is why they did it.
Although it is ultimately personal choice and preference, there is absolutely no debating the fact that the handling of the M5 is crippled by the thin front wheels in its OEM configurations.
I currently can compare back to back whenever I want, as my M5 has the 275/35/18 with OEM 9.5" wheel on all four corners where as my wife's M5 is on the stock staggered M5 set up (for now). The difference is night and day in anything more than putting along in town traffic.
Being on the track, carving the tail of the dragon or some country road, there is simply no comparison.
If the performance is not something that will make you switch, the wider rubber and the bigger lip on the 9.5" wheel should be the sole reason to make you switch.
PS, dee007, this ISN't a chat room, stop posting one liners in each post. Compile your thoughts in one post and THEN hit submit.