Aside from the obvious (tire pressure, balancing), do this:

Check the tie rod ends and other suspension components for play. You'll have to lift the front end up and unload the suspension to check.

 

Mine kinda feels like that when I'm behind semi's

 

That's just buffeting from the turbulence coming off the truck.

As for the OP's problem, I second the unbalanced-tire suggestion. I had the same thing about 65mph, and it went completely away when I replaced the wheels and tires.

 

when i got the same shimmy's, almost that unbalanced feeling. i found out my TRE's were shot.

check your Outer TRE's. check the boots, and if u can have it on a lift, check for any play. that was the culprit for me. and like you, above 80mph it would shake, but once i got it fixed, no more shimmy/play.

another culprit might be a wheel bearing..but i'm almost positive the play your describing is your outer TRE's. hope this helps :wrench:

 

I'd say give is some info about your car, year, mileage, etc.
There are many reasons your car cut do what you stated.
I ran my Wifes 2003 GL from WI to SD and had no problems doing well above 80.
Her car has 63k Miles on it.

FS

 

If it's your TREs, your car won't hold an alignment. Is your steering alignment alright?

Also, you might have a smelly Isaeli sleeping in your belly pan and he starts running around when you hit 80mph. Or you have a bad trunk monkey.

 

TRE's and/or out of round tires

 

milage is 50k
yr 04

smelly Isaeli...haha idk about that one !

my wheel holds alignment for about 20 feet then it slightly turns to the side.

 

Mine does that too, but at some point north of 125mph

 

I have the same issue but I KNOW my TRE's/suspension etc is all good as they are practically brand new, but I do have a VERY slight off center steering wheel so I'm sure an alignment would fix it. Just been lazy to do it.

 

i dont think an off center wheel can be fixed with balancing... maybe if it really is a small amount, but when i got my dash harness replaced, the d bags put the wheel back on at a queer angle.... kind of annoying....

 

alignment, not a balance (which is for your wheels/tires).

 

i kind of feel like its unbalanced when on the highway driving over 80 mph.

Its only feels like that when i hit over 80.

I grip the wheel tight and it still moves left or right by itself...really strange

Is there a possibility that what you're feeling is actually tramlining?

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=47

 

i took the car to the service center, it is being taken care of as i speak, hopefully they will let me know what the problem is.

 

also when i make a turn on my car, i hear a cluck cluck sound coming from my wheel?.. any idea what that is?