I got caught in an early snow storm with the OEM bridgestones, it was sketchy and down right scary they are not for snow at all.

I would try to get the dealer to swap the tires for a set of Conti DWS they are great all season tire but no run flats. They should do this straight across as run flats are more expensive. 20" winters are not cheap I bought replica 214 in 9.5 and 10.5" so I can run 275/40 winters all around on my wife's diesel. Next year for my M I will get 275/315 20" on the OEM wheels.
Or ask to get a set of OEM 19" style 298 they are the winter wheels that are made for the ///M but they are terribly ugly in my opinion.

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X5M Eisenmann exhaust, de-Catted down pipes, 22" HRE wheels, ECUProgram stage II (700hp) tune
X5 35d Tuned and Lowered