Just changed all four tyres to non-run-flat tyres on my 2010 320d m sport coupé. And i must say its a much smoother ride,when i rang BMW for there opinion,they said they didn't advise it as it might affect the warranty.....so i rung the BMW warranty people 08712000199 to check it out..They told me it WOULD NOT affect my warranty in the slightest.BMW just want you buy run-flats at high price about £1300 for four.
The tyres i bought were Falken FK453 xl 225/35/19 front and 255/30/19 rear,total price £626 fitted.Got to buy a space-saver now 3.5x17 et8 rim.
Hope this has been some help to all that are undecided !!! GET RID OF THE RUN-FLATS.