Vibrations at 45mph and then at 65+mph

[Scainjr]

Alright I have a 2006 gmc sierra running 20x14 fuels on 35x13.50 fuel mud grippers, and I'm getting a bad vibration/shimmy at 45mph and 65+. I've had them balanced and there good, and I've had the truck aligned 3 times. I have completely replaced the entire front end and the ujoints in the driveshafts, I have tried running these at every psi from 35 to 62 and I still get a vibration sometimes worse at lower psi. Any thoughts would be greatly appreciated?

 

[Mrhorsepowerlsx]

Do you feel the vibs through the steering wheel? Or do you feel them in your butt as you drive?

 

[Bonecollector]

I'm assuming your truck is lifted? If so do you have steering stabilizers? You may be experiencing the "death wobble" I know the ford and dodge 1500s get vibrations and shimmying really bad without the stabilizers when lifted 6" and have 35s

 

[2003tahoe]

Try looking at wheel weights mine had same thing at 60 when im going to school scared the hell out of me when i was at wot trying to piss this lady off that was weaving in and out of traffic but i still pissed her off, also try looking into the kyb stabilizer and get a boot from autozone works great for me.
Ignore the weights i didnt read sorry lol

 

[Swampfoxjr]

hub bearings maybe?