I also had the run-flat Dunlops (factory provided) on our 2008 535Is and just put on four new Kuhmos. They are a vast improvement over the harsh riding run-flats and I'm very pleased with their low noise level and performance. I would never by another set of run-flats. Especially since I have a spare from the factory. Why would I need them? Go with a HP radial of your chosing and don't look back.
This topic has come up in the e60 forum site. I think you'll find the same sentiment. Run-flats are harsh after a couple thousand miles and are not forgiving. Regular tires are softer, stickier, and can be repaired. They are also a hell of a lot cheaper. Best summer tires Michelin Pilot Sport PS2, and best winter tires Bridgestone Blizzaks.
