Joe16XLTSport

I have a 2016 F150 sport with the 20 inch six spoke wheels. When I get to speeds of about 80-85 on the interstate I feel a vibration in the whole truck. The passenger seat shimmy shimmy/vibrates kinda rough in my opinion for a new truck. I took it back to the dealer and they rebalanced the tires since it is a month old with a bit over a 1000 miles, but it is still happening, and the dealer basically is scratching there heads. Any suggestions???