Most people dont feel spending 2000.00 on tires every 12,000 miles or so is normal. but here is one of many links to the 5 series.»www.arfc.org/complaints/2011/bmw···lem.aspx
Bottom line is tho run flats are not any good on our roads here in the northeast. They just dont have sidewall flex or the suspension to handle these roads. but i still believe the op is just beginning his tire adventiures with his car.