Well, I posted the list a few weeks ago about the exact same
thing....someone replied to check each tire very carefully.  I pulled the
tires one by one, and sure enough found the right rear had a major misformed
tread area.  Looked like a belt inside the tire busted or some other
catastrophic occurance.  Anyway, check each tire very carefully, you may
even need to run your hand over the tread surface as well as the sidewall.
Worked for me.

Mark

>That's what I feel when I drive - Thump Thump Thump - I am running out of
>ideas.....
>
>It's Speed related, (feel it when slow or fast, just thumps faster) doesn't
>appear to be a separated tire, front ball-joints OK.
>