I have vibration at highway speeds , I've rotated and balanced my tires, changed u joints, added hub centric rings although the vibration lessened after the hub centric rings were installed. I don't know what else to do. Any suggestions?

 

A bent rim will do that also

 

How can I have my rims checked ?

 

A good way to tell is by how many weights they need to put when you balance your tires... if there isn't many, you will want to bring them to you local tire shop yo have them tested.

 

a tire shop can tell you

 

Have you checked the steering components?
It could be you have a tie rod end going bad, if you are running over size tires it puts a lot of strain on that system.

Also you mentioned u-joints.
Is this truck 4-wheel drive?
So you are talking about the u-joints in the front axle?
I had a friend at work once with a CJ-7.
Couldn't figure it out, even after putting in a steering stabilizer.
Ended up being a bad u-joint in the front axle.

It could also be a ball joint going bad.
I would just give it all a really good look.

Radar

 

My Blazer is 2 wheel drive