Vibration/shaking with empty trailer

So I got all new tires all around and all new shocks all around. Pete 579
Im still getting vibration/shaking when Im driving with a trailer on highway, notice it a lot more when empty. What could it be?
-Do I have to adjust ride height when I get all new tires? The thread on these General HDs is huge.
The truck vibrated even before getting all new tires if I remember correctly. So now Im not sure what it could be.
-Bad leveling valve? How exactly do I check for that?
-Something mechanical? I do notice when I go over even a small bump - the truck hits hard, it didnt before. King pins? Leaf springs?

Any ideas?

 

Vibration 60mph+, going to get steers balanced tmrw and see what happens. Driveline seems good, all 3 axles aligned.
Not sure how to see if my rise height is bad, was adjusted to spec last year at Peterbilt but that was with my old tires, so idk
Im running new Michelin's in front and General HDs on drives

 

Balance of steers all good. They're saying my new drives should be deflated to 95psi since I only do light loads (theyre at 105 now), and the drives are only running on the middle blocks of thread.
Would something like that cause vibration?

Have no idea how to adjust ride height or how to properly measure middle of axle to bottom of frame. Theres no set point to put the measure tape against so idk

 

Vibration seems to be coming from the front (or maybe below me), goes on and off, almost like it has a cycle that it keeps repeating. Starts at 60mph I believe
Pressing pedal or not, same thing