I have a 98 1500 4x4 with 183,xxx miles that I just got about a month ago. It's been driving great for about a month, but about a week ago I started getting a vibration coming from the front pass wheel and it only happens when I hit like 40ish mph and will stay until I stop and turn the wheel, like to turn right or left and it will go away but as soon as I hit about 40mph again, it will start again. And it doesn't happen ALL the time.. but fairly recently.
I know its not the wheel being off balance because its not consistent and it doesn't do it only under breaking, so I don't think it would be a rotor.
What do ya'll think it could be?

 

Wheel bearing ...jack the front off the ground and grab the tire on the top and bottom...push and pull back and forth and i bet there is play .

 

My truck does it too.... but I've been told its due to alignment issues. I had a wheel bearing go bad and it wasn't even a noticeable shake. But my truck is crazy.

 

it doesn't move when you grab the top and bottom, but it does move when you grab it on the 2 sides of the wheel.

 

Start looking at parts, and see where the slop is. Also check the track bar......

 

A quick and easy check would be to swap the left and right front tires and see if the problem moves with them.

One of the tires may be going bad from hitting a pothole or plain old wear and tear.

Mine does this starting between 50 and 60, depending on how rough the road is, and sometimes does not do it at all. Swapped front tires left to right and the vibration seemed to move too.

Oddly enough, the problem got WORSE after I put the new ball joints and tie rod ends in. My theory is the slop in the old worn out parts was masking the vibration to some extent. Which is pretty frightening.

Putting new shocks on helped quite a bit, but the problem is still there.

Time for new tires for mine anyway.