HI [8D] As soon as I reach 60 mph my pickup starts shaking And when I reach 70 it gets really bad . At 75 -80 I feel like the shaking is so intense I have to slow down.I just put new tires in the rear and had them balanced. The front tires are in good shape. Im hoping someone out there might have a clue to what it might be before I bring it to a shop............

 

well off the top of my head i would say they are not balanced correctly.