93 2wd s10 blazer. If I get above 65mph I get a bad vibration, sometimes it feels like the truck is going to shake apart. it only has 90k miles, I put new tires on it, It did it with the old tires also. I'm pretty sure the wheels are still straight, I'm the second owner, an older lady had it before me. I think I've got it narrowed down to either a stock u-joint that has siezed up from setting up for 10+ years, or a warped rotor, because I've noticed that after 75+ miles the brake dust on the driver front is a whole lot thicker than the dust on the passenger side. Anyone got any other ideas? It's not a major issue since I rarely get on the interstate and drive that fast, but i would like to get it straightned out anyways.

 

When you got the new tyres [tires] did they balance them?

 

Have the balance re-checked at a different tire shop.
Have a shop replace both u-joint in the drive shaft and have the shaft balanced.
With the truck in park/neutral... rev the engine and determine if the problem is there.
A warped rotor will not cause a balance problem.