Originally Posted by Eelesy24
It is fine to mix them front and rear.
I work in a BMW dealership and recently we had a customer who wanted to know if swapping to non run flats was approved, and as we couldn't give a definitive answer we emailed BMW technical, and their response was yes it is fine and they said the best way was to swap in stages, with the rear axle first, and then the front at a later date.
Don't believe that as a response from BMW or your dealership. If you work at a dealership then you will know to AUC a car for the forecourt, if it hasn't got RFT tyres on a car that should have them as OE equipment then you need to fit them to retail it.