I recently bought a 2016 SV Crew cab. Of course once I get it home I realize it has the vibrations. The vibrations would come on at various points from 60-75 and felt like an out of balance tire. I had them balanced, rebalanced, road force balanced, balanced again, an out of round rim replaced and still they vibrated. I swapped the spare for one of the rears and also replaced one of the rears.... still a vibration. I rotated them and adjusted the pressure. I took it back to the dealer for the third time with some video of the seats moving and they finally got serious. They finally determined that the tires had flat spots and replaced all 4. Turns out the truck had been on the lot in Florida for a few months. The Hankook tires developed hard to detect flat spots which vibrated the truck at highway speeds. The hot pavement just warped the tires permanently. Not until each and every tire was replaced was the problem remedied. After replacement, no more seat shake, perfect smooth ride. I thought others may be interested in my trials as well as the final solution. From this experience I have developed two new rules for myself. Always test drive a vehicle at 75mph (the truck was great until 60mph) and never buy the vehicle that has been sitting for 4 months.