My Second Load.....Bad Vibration in Tractor.

So I'm delivering my second load as a solo driver today. I'm driving along and notice this pretty significant vibration in my sleeper. It isn't constant. It goes away for about 2-5 minutes then comes back for two to five minutes. The vibration starts out lightly then gradually picks up to where it's shaking the entire sleeper. It's not so much in the cab as the sleeper but I can feel it in the seat. My steering wheel isn't shaking or anything. Then it slowly fades and goes away for another 2-5 minutes where it picks up again. And it goes on and on like this.

My first load from Illinois to Baton Rouge I didn't notice it. It seemed to start when I picked up this trailer I'm hooked to now. I am driving a 2014 Cascadia. Any ideas? Seems my shop doesn't have a clue. Oh yeah. I also had a new rear drive tire put on yesterday. But the shop said it probably isn't that if its not a constant vibration which I agree. Could it be something about the trailer? It's literally driving me crazy. The sound and rattle for 11 hours a day is killing me.

 

I hadn't noticed it when I was driving with another trailer or while bobtailing. It seems to happen when I get between 60-70mph. I think I'll deliver this load and when I hook to a new trailer I'll see if it continues. If it does, I'll have to take further steps. I inspected all the U joints and tires. Everything "looks" to be on the up and up. As stated, I just put a new tire on the rear drive, but didn't notice the vibration after I put it on and with my last empty trailer. It seemed to start with this loaded one.

 

I

ts not the road surface. It happens on smooth road. And rough roads. I have 850 miles to my drop. I'm gonna run to TA and disconnect my trailer then run her up to speed and see if it still happens. Shop told me to take her to TA tire shop to see what they say. Just what I need.