These are only two of many possible causes.
Tires need balancing?
Warped brake rotors will cause pulsation (or vibrations at high speeds) when the brakes are applied. This may also go on to misalign the calipers and cause other vibration related damages.
These vibrations change speeds and directions when they go into different layers of the Earth.
I had a similar problem once and it had something to do with my brakes, I'd get them checked if i were you
I had this happen. It was the wheel bearing. It starts off as a faint whine, but over time as the bearing gets worse it becomes a squeal at highway speeds and a squeak at low speeds. If squeaking at low speeds the bearing is on its last legs and total failure is imminent probably causing more expensive damage and repair.
check your wheel bearing / hub bearing assy
When a TO bearing starts to go bad you will hear noise when you push on the clutch. Also shifting will be more dificult when at slower speeds.
Tire out of balance, bent wheel, or defective wheel bearing are common causes.Tire out of balance, bent wheel, or defective wheel bearing are common causes.
A dry wheel bearing will cause the rear wheel to squeak at low speeds. The wheel bearing should be checked immediately to avoid a major problem.
Bad wheel bearing.
you have a definete wheel bearing problem. have it replaced asap
Have your truck alligned. Vibrations on low speeds means your vehicle is out of alignment and or worn or damaged suspension parts...