Car people are obsessed with the idea that no-one wants runflats. It stems out of the original ones - now 20 years ago - having excessively stiff sidewalls which caused the ride to be crashy. Times has moved on and RFTs have got a lot better. I have a friend that had an early E90 and, in putting on a set of second hand RFTs a few years ago, found them to be fine. My set of 201s had 3 normal tyres and 1 runflat - I never noticed until my eagle eyed friend pointed this out to me and even then I still couldn't tell from the drivers' seat.