Tires: Bump in the tire, thump thump, rav 4

Question
It sounds like one of the rear tires on my Rav 4 has a bump in the tire.  When I drive I can hear a thump, thump.  What would be the cause of this and is it dangerous?

Thanks!

Answer
Shana,

It sounds like you have a tire with some irregular wear, and that is caused by misalignment.

But it is also possible that this is a tire starting to separate.  The way to tell is if this problem started developing over the last hundred or so miles and is gradually getting worse.  This is quite dangerous and should be taken care of immediately.

But if it is just irregular wear, this isn't dangerous, just annoying.

Have someone look at this right away.  A knowledgeable tire guy ought to be able to tell the difference.