Again, why shouldn't they say that? Surely the car has been designed to have run flats and by changing them, you're altering the characteristics of the car, potentially affecting safety.
If you did want to fit non-RFT though, all it would take would be someone to look at them and say, "yes, he's fitted the correct size and load rating of tyre for the car and not tried to stretch a fucking pram tyre over a set of 20s, reducing the amount of grip the car has, just because he thinks he looks 'well bad blud, innit'!"
57 Sapphire Black E91 330d M-Sport
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