Tires: Flat spots on rear drivers side tire, hyundai elantra, futura tires

Question
Hello, I purchased 4 new Futura tires (Pepboys) about 2 years ago (~40K ago) and just now rotated them (I know, horrible) but when I took off the back driver's side tire I realized there were flats spots alternately all around the tire.  There was a flat spot on the left then on the right and so on alternately and the tire was in REALLY bad shape.  The other 3 tires seemed to be wearing fairly normal.  I have asked around and some people seem to suggest its a bad strut while others think it is from not rotating them.  The car is a 2001 Hyundai Elantra with 105K miles.  I have pushed down on all four corners and there only seems to be about one bounce after letting go to check the struts.  I am wandering should I replace just that strut/ or both back struts, or just replace the tire and get an alignment?  I am hearing several different things, could you please help?

Answer
Sorry, struts are out of my area.  So you need to have it checked.

But it may be the tire.

First, those tires are junk and known for problems.

Flat spots only come from braking.  Lock up the brakes.
It only takes one lock up to get flat spots on a tire.

I would recommend getting the tires balance, and if the problem does not go away then I would suggest getting new tires.
Do not get alignment until you fix the problem or new tires or you will waste money.

John