My 545 came with the Dunlop DSST runflats and I can't really notice any difference in the "harshness" of the ride over the Michelin Pilot Sport A/S tires on my 330.

I'm very curious to see what the treadlife will be for the runflats. I am fairly certain that I will probably switch to "regular" tires when it's time to replace the run-flats; if only to get the benefit of the lower weight.

I got over 30,000 miles on the OEM Michelin Pilot Sports that came on the 330, and when I replaced them, I was only beginning to see the wearbars in the tread.

-MrB