High speed vibrations Options

[Coligion]

My car just hit 96k miles, but this high speed vibration issue has always been a problem. When going over 55 mph, I'll get a ton of vibration from the steering wheel. I do have aftermarket wheels/tires. When I first bouht the wheels, I did not have centering rings and believed that would solve the problem. No dice. Even after getting the correct sized rings the car still vibrates. Before getting the rings, I did have the alignment and the wheels balanced. I wouldn't think inserting plastic hub-rings--in the center of wheel--could offset the balance, right? The shock/struts are relatively new, so it couldn't be that. Also, the car had this vibration problem even with the original wheels....Any helpful advice is appreciated.

[Stambo]

For checking ball joints you have to jack the lower control arm up some so you'll be able to feel if the ball join is loose or not. Check that by lifting the wheel up and down, and put one hand on the top of the tire and the bottom and wiggle back and forth. If its bad it'll be obvious.