I would cancel. Put the money towards a 2nd set of rims for winter use or add it to your BMW Extended Warranty budget. My work takes me to DC all the time and driving around in RFTs is a joy. Only because the road conditions are good. Obviously DC driving in winter weather is another story. I've got that covered with a brand new set of OEM rims with winter RFTs. Good luck.
BTW, I have 19" rims for summer use. For winter, I went with 18" rims. Pretty happy with RFTs so i'm going to stick by them.