I got my RX350 for 2 months and the cars originally came with Michelin Latitude Tour HP. However, Michelins are just too stiff and whenever the car hits the bump, it is like a concrete tire hitting a solid bump and shock just sent straight to my neck.
Dealer agreed to swap Dunlops from one of their 2013 RX loaner to mine. Ride comfort difference is immediately noticed. Bumps are softened and no more harsh shock to my neck.
3rd gen RX suspension is stiffer than 2nd gen for sure and I still feel bumps. But with Dunlops, ride is softened well over bumps even on bad San Francisco roads. Road noise is louder than Michelins but it is still ok. Steering feel a bit less responsive than Michelins. However, ride comfort is my top priority. Will buy again if these tires can last 40K miles.