Even took the tire off to patch it with a radial plug and found the rattle to be inside the tire. is the pressure sensor loose or did it break when I was drving down the road at very low pressure? can it be tightened up by the external nut on the valve stem? something is loose and it rattles on the rim, that sounds like im dragging some metal parts behind me on a string.

 

I've never had one come loose, but had many broken inside the tire..the sensor screw to valve has loctite already in the treads so it doesn't back out, but can only be seen with the tire off the mag..but if the sensor has been free in there for awhile and even if it came loose...would assume it's not in 1 whole piece...

If the external nut was loose on the outside, you would be able to move the valve around or push it inwards slightly...

 

it turned out to be a handle of a plyers that entered the tire, was not quite all the way in for sometime and then it fell in the tire, causing a leak, with no visible nail or cause. pulled the tire off and there it was. a metal handle of a pylers. weird!!!