Resonating / Vibration Highway Speeds

2000 Windstar, fairly new to me (a year). It being shaking at 57mph and shakes violently at 65. Even the 3rd row seat is vibrating bad. We have been driving about 55 on the highway to avoid shaking.

The front tires are severely worn. I know this could be the cause but I thought of them as more of a side effect. I did replace a tie rod end on it 4 months ago but it was doing this before that.

Are there any other specific things I should check or should I just replace the front tires and get an alignment?

Your advice is appreciated.

I would do the tires and alignment as soon as possible.
A good alignment technician will give the front end a good shakedown.
Make sure to tell them of the problems that you are having.

I agree with Wiswind's advice. On two different vehicles I have had vibration problems that turned out to be tires. In both cases they were tires with a fair amount of tread left but were de-laminating ( I concur with the tire manufacturers that at about 6 years it is time regardless of tread). You may be saving yourself a larger problem- tire failure at high speed.

Good luck