I replaced the Continental ContiSport Contact runflats on my F30 328i with a set of Continental ExtremeContact DW in the same size: 225/45ZR-18. The improvement in ride quality was dramatic. Road noise dropped off significantly, especially when hitting expansion joints or potholes. That high frequency "thwack!" the runflats made is completely gone.
With proper selection of a replacement "traditional" tire, you can have your cake and eat it too, with no loss of steering response or grip. I have a second set of wheels with Bridgestone Blizzak (also NOT runflat) for the winter, so I'm always optimized for the conditions. Couldn't be happier.
I'll be purchasing a 2015 X1 xDrive28i for my wife tonight and, as soon as we take delivery, I'll be ordering another set of these tires for the new car. This is a no-brainer.
I also have one of these in each of my cars:
http://www.griotsgarage.com/product/...+compressor.do
