Non-run flats.
Significant ride improvement. So less harsh it is a different car!
Tremendously more quiet. I can turn the bass down a number or two. (although the run-flats were quiet for the fist 7000 miles too)
Substantially better handling - show me those manhole covers now!
Old tires: Potenza RE040 run-flats
New tires: not a salesman so it doesn't matter - anything non run-flat!
-shoe