I have just bought a Cayenne, 3.2 V6. I'm delighted with it. 95K, full service history, drives nicely, although quite a firm ride compared to previous cars (Mercedes ML, Volvo V70).
It is currently running 275/45 R19 tyres (I live in England, sorry about the spelling).
I am an old bloke, so comfort is a factor in driving.
I would be very grateful for any comments / advice on whether switching tyres would make a significant difference to ride comfort. The roads where I live are so crowded that you're usually just boot-strapping, so high-speed cornering is not really an option even if I wanted to! Would a higher profile set of tyres be worthwhile?