Tire situation

I purchased my car 2 months ago. This car is certified pre-owned by BMW. The dealer installed 4 new tires before I purchased it. Now my situation...
As I was cleaning my wheels, I noticed the tires the dealer put on are NOT run flat tires. They are summer performance tires. I cant believe I did not notice this before. I called my dealer and they are checking into this. It sounds like they will install 4 run flat tires at there cost. I do drive this car in the cold weather where I live (no snow driving). It does not appear any all season tires are made in my size (275-35-20 and 245-40-20). My only choice appears to be Pirrelli P Zero's. I am half tempted to leave the tires I got with the car on it. I just dont want to get stranded anywhere. Does anybody know of a all season run flat tire in my size's ? I also wonder if BMW would requirer run flats to be put back on the car in order to have it pass certification?