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.

[Coligion]

I appreciate all the responses

AMCMoe, how do you recommend checking on the tie rods and ball joints?

Mstoochn, the speed at which the vibrations begin is fairly consistant. I don't notice anything until I hit 55 - 60 mph. I also have never noticed a hop or specific speeds (other than high speeds) that trigger the vibration.

samir0189, the wheel vibrations are pretty constant, regardless of acceleration, deceleration, or braking. As long as I'm going around 60+, they are always there.

Something else to note....there also seems to be some vibration at the gas pedal while traveling at those speeds. Not sure how much of that is normal or if it could be linked to my steering wheel vibrations....