A number of your readers have been advised over the last couple of years to switch to 16" wheels in order to improve the ride quality over that achieved on 17” or 18" runflats. A much simpler, and cheaper alternative (assuming there is a spare tyre well in the boot) is to fit non-run-flats of the same size and specification as the runflats. The ride harshness will disappear and the tyre pressure warning system will still indicate a puncture, allowing the driver to pull over safely, often before the tyre blows out. I have done this to my Audi on Sport suspension and 225/45ZR x 17s and the difference is amazing.