When I am driving down the highway generally around 60-65 mph the car shakes. Sometimes as low as 55 mph.

-The shaking only occurs when I have my foot on the gas pedal.

-I change my brakes, balance my tires, and get new tires often because I am constantly driving. (I am a delivery driver)

-The rotors are not warped in any way and the shaking does not occur in the steering wheel.

Does anybody have any suggestions?

 

Have you had a four wheel alignment?