2007 Dodge Grand Caravan Vibratiion

I purchased a 2007 Dodge Caravan used. It has 21,000 miles on it. It has had a vibration in the steering wheel since I purchsed it. I took it to the dealer and they said the tires were bad… I purchased 4 new Michlen tires and it still vibrated. The dealer has a machine that they can put tires on and it checks them and the wheels. I forget what they called it but it putes pressure on the tires just like its on the road. They said the new tires and wheel were OK. But I still have the vibration… I noticed the other day when I got on a newly paved road that I didnt have any vibration the whole time I was on that road. this was on an iterstate hwy. and soon as I got off the newly paved road the vibration was back… any suggestions.

It could be, and I’m guessing here, that the tires are overinflated.

A lot of variables needed here. How fast are you going when it starts vibrating? Is it a sound or do you feel it? Does the frequency of the vibration increase with speed or stay the same? Has it ever been in an accident? Do the tires have any funny wear paterns? (or did they on the old tires) like feather or cupping? Does the steering wheel shake at any point? Does the vibration go away when you hit the brakes?
Does this still have a waranttee on it?
Can you take the Mechanic for a ride so he can experience it too?
(too out of breath for any more questions).

does it vibrate when you go over a slight bump in road? Front sway bar mounts to chassis in two places, each mount has a $2 rubber block in it that wears out and produces a rattle.
These are easy to replace as they are held on by two nuts and a clamp.