gtp1500

Hi everyone, I just purchased a brand new 2018 2500 crew cab tradesman, it had 12 miles on it so on the way home I felt a vibration like a tire out but the roads in OK can be kind of rough so I wasn't sure, I get back to KS on some roads I know were smooth and I've got a vibration that comes on for 30 seconds and smooth as glass for ten. The vibration comes on gradually, gets pretty bad then gradually smooths out. All of this is at 65+. Got an appointment to a local Dodge dealer in a week but I took it to Firestone to get the rears balanced, said they were out 2 or 3 oz. Still shaking so I'm going to get the fronts balanced tomorrow. I've uploaded a video to YouTube but not sure I can share? I've read of some horror stories on this subject.
https://youtu.be/CuDD8XqA370