I replaced the run-flats on my Z4 with Conti. Ultra High Performance radials and carry a can of sealant and an electric pump in the car in case I have a flat. I much prefer how my Z4 handles and rides without the run-flats. When we were looking for a new SUV for my wife we opted for an Audi Q5 over the BMW X3 because BMW will not replace the run-flats with regular radials.Count ourselves lucky we didn't have the first generation of BMW with runflats , they were so bad they changed the suspension to accommodate the rough ride. They are a bit more pricey as well but although I never had the pleasure of putting them to the test they are quite impressive in testing.