I had a similar story with my E90 several years ago. Blowout WITH a RF tire on. Of course it happens at 7 PM or so on a Saturday, so I am screwed. Had it towed back to my dealership (thankfully close to home), but without a car for three days by the time my car had a tire back on it.
It is ok if BMW wants to add safety by using RF tires. But it by no means should be a replacement for a space saver spare.