I have checked the wheel bearings, multiple times. They're perfect as far as I can see. No play at all in any direction, no roaring noise/sound either and no play in any of the ball joints.
I recently talked to somebody who had vibration in a DTS. He had a crack in one of the rotors. So I checked those too. Nothing wrong. no different or extra vibration while braking.
The decrease in vibration I noticed when it was a really hot day, was fenominal and the only thing that was different in my opinion, was the temperature of the tires.
In the mean time......I turn off the traction control a lot of times to speed things up as far as wearing out of the tires go and tell myself that it's good for the enigne too, just to have an excuse....