My dad just sold his 335, and remembered that he took these tires off a couple months after he bought it (he doesn't like runflats). He purchased it new from BMW and these came with the car from the factory.
They are OEM Michelin Pilot Sport PS2 Runflat Tires
These tires have about 2,000 miles on them, and have been sitting in our basement with industrial trash bags over them - pretty much brand new condition. From Tirerack they're $1,400.
Local pick-up in Northern Virginia.
Asking $1,100 - feel free to make an offer.