Bad vibrations 2001 A8L

New tires just had front end checked no Problems:
Problem Im having is a low hum & vibration that I'm feeling at various speeds 55- 65mph less noticeable as I increase speed to around 80mph feelings as if it was right under the car. I also have been experiencing that when I put the car in park on an incline that it seems to roll a little more than it should ( this was just to test I usually use emergency brake) in other words, in park I can move the car a few inches, is that ok
Doesn't seem right
Greg