Tires: steering wheel shimmy at 35 mph and below, toyota avalon xls, steering wheel shimmy

Question
QUESTION: 2003 Toyota Avalon XLS. Goodyear Assurance Comfort Tread tires with 27,000 miles;7/32 tread remaining. Steering wheel shimmies on smooth asphalt pavement and swirl surface concrete roadways at speeds up to 35 mph.The shimmy will stop instantly when a more coarse roadway or less textured concrete roadway is entered. Alignment and wheel balance checked out OK twice within past three weeks.
A tire rotation three weeks ago caused the problem to become more apparent.Is it possible that the shimmy is due to a structural breakdown within the Assurance tires? Please advise a procedure to check the tires for structural flaws. THANK YOU!          Tom

ANSWER: Tom,

There are a lot of things this could be - and tread separation is one of them.  But what bothers me is that the problem goes away on coarse textures - and a separated tire would not do that.

But just to be safe - put on a pair of gloves and rub your hands circumferentially around each tire.  A bulge will indicate a separation.  Lack of a bulge doesn't mean there isn't one - which may develop later, so do this every 2 or 3 days for the next 2 weeks.  If the bulge hasn't appeared by then, it isn't going to.

I'm guessing CV joints.  Does it matter if you turn?

---------- FOLLOW-UP ----------

QUESTION: Followup to experts question; The shimmy tends to disappear while turning.

Answer
Tom,

That pretty much eliminates a tread separation - they would get worse in turning mode.

So I'm leaning towards something mechanical - CV joints (but they generally get noisier on turning), or a worn tie rod end, or some other steering component.