stock suspension? should fit
Try posting on the e39 board to be sure -- plenty of folks have done this and you should be able to get some first-hand feedback. But with stock suspension heights, there should be enough extra room around the fender lips. Lower the ride heights with different suspension and all bets are off.
Expect some slight degregation in noise and comfort with lower profile tires. Also, the OEM M5 wheels are not particularly light; you're likely going to add some weight over 17s.
Not trying to talk you out of it, but since you already have winter tires/wheels, you might want to consider putting max summer performance tires on your 17s -- might give you better performance than your current tires without any trade-offs (cheaper too).
Cheers. '01 M5
Re: stock suspension? should fit
Thanks, I appreciate your feedback.