Tirerack has a whole list of non run flats that will fit the OEM rims. I recall reading that you can't put run flats on a non-run flat rim, but you can put regular tires on a run flat rim. Believe the run flat rim has an extra flange. Anyway, lots of info on other BMW forums that support non-rfts on rft rims. I'm going to make the switch myself when the rfts wear down. Good luck!

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E70 X5 3.0si Space Grey

E36 Z3 2.5i Roadster, Sterling Gray Metallic