rear end vibration

[patrick93]

I recently had an alignment done because i was noticing uneven wear on my tires and the car pulls to the right. I also had all 4 wheels rebalanced.
But when i drove home after the service, the car's rear end started vibrating at about 55 mph and gets worse as I speed up. The vibration kind of goes on and off. It would vibrate for a second then go away then it will start to vibrate again. It also feels like the rear end swings out a bit to the left when the vibration happens. So I went back thinking it was a balancing issue but I they told me that the tires are perfectly balanced and the tires are still in good shape.
I drive about 120 miles everyday to go to school and driving this car on the freeway during rush hour with this kind of problem is really scary. So what can possibly cause this vibration after getting an alignment done?

[Bitter]

Are the wheels loose?

[patrick93]

When I got home I checked the lug nuts and they weren't loose

[Bitter]

But are the wheels flush on the hubs? Did you loose a wheel weight? Is a wheel bent?

[Woz2000]

How about rotate the wheels/tires and see if the problem moves. You can do that yourself in under 30 minutes.

[speedy25]

If the problem moves with the tires you have a tire issue. If it stays in the back its a mechanical issue. It can be struts, suspension bushings or a hub about to fail.

-SP