Apparently the M5's massive brakes make it difficult to fit anything under 20". Tirerack doesn't offer anything under 20".
There is a 19" BMW M5 wheel, however. Model 705M. It is sold in
"Orbit Grey" as the default wheel for a base M5. Base M5's come fitted with 265/40 R19 for the front and 285/40 19 for the rear. The wheels are 9.5" and 10.5" wide respectively.
BMW recommends buying the 705M in
"Ferric Grey" for winter tires. These wheels only come in the size of the front 9.5" wide wheels so that one can go with 265/40 R19 winter tires all around.
I really do prefer the orbit grey finish but unless I buy 4 new front wheels I will get a staggered set. I will likely not drive the car in real snow.
This video shows just how good the MPS All-Season 4 are in all but the worst of winter. So how bad can a staggered set of winter tires be?
Realistically, I could buy used from this place (seems to have good reviews), and get:
Used set of Ferric Grey square setup with used winter tires already mounted, or
Used set of staggered Orbit Grey with summer tires mounted that I can burn through.
Any thoughts are welcome.