additions - my tires are fairly new , they have about 6k on them.

The vibration is heard not much felt in the handling of the car - it sounds like something is resonating and I am running on the side of the highway all at the same time ,
the car doesnt shake or anything , just that sometimes the vibration is bad enough that it causes other things to vibrate in the dashboard like things in the ashray or anything not tightened up.