Hi Martin,

I'm afraid it's impossible to assess a 'whistling sound' remotely, so perhaps get a second opinion from an independent mechanic if you have any doubts on that one.

With regards to the tyres, BMW does not recommend fitting regular items to replace the run-flat tyres, but it is of course possible. Make sure the overall dimensions are unchanged as that affects the gearing of the car and most likely the speedometer reading, too. Also, you'll need to come up with a solution for a spare as well, which the boot is unlikely to be designed for.