What is the cause for front end vibration @ 50-65 mph on 2006 Ford Freestar

The wheels were balanced and was told that all 4 wheels were bent! No rough roads, potholes or damage otherwise to vehicle. Help.

Asked by for the 2006 Ford Freestar
have them SHOW you at least one of the 'bent' wheels while it's mounted on a wheel balancer.Will prove 2 things if they are right .1) rim is bent, 2)It needs replaced to get rid of vibration , balancing won't fix a bent rim or a bad tire.