So I'm rotating my wheels this morning and as I roll the left rear tire up to the front I hear something rolling around inside the wheel. What could it be, a loose tire pressure sensor? I don't have any TPS warnings and the system seems to be working fine.

 

Who knows. I would have the tire removed and the offending piece of whatever removed. Inspect the TPMS at the same time. It's the only way to know.

 

What ever it is it wasn't loose 5,000 miles ago during the last tire rotation. Guess I'll take it in to see what's in there...

 

I know its likely no help but back around '68 I'd put a set of dunlops on my TR and after about 3K miles they started vibrating like out of balance only at all sorts of different speeds. Had one pulled off and discovered that the interior wall of the tire was coming off in little pieces and at speed would plant themselves where every they happened to be at the time. Only two of them were doing this. Never figured out why.

 

There is the possibility that it is a small rubber ball. They occasionally form inside the tire, forming from little bits of rubber dust, time and heat. I've pulled some out almost the size of golf *****, though not on my Mini.

Have you ever run with the tire low on air for an extended distance?

 

Report back when you find out, it'd be interesting to know.

 

I read that somewhere, it didn't sound round though as rolled the wheel and I've never run the tire low...

The car's running fine, no vibrations or anything to indicate a tire out of balance. I'll let you guys know what I find.

 

I found a wheel weight inside a tire once. Still all shiny. It must have somehow fallen into the tire when it was mounted.