You should be able to get these at automobile supply houses or tire stores. You may confuse an inexperienced person when asking for a metal stem.
Valve stems have a standardized number on them, regardless of manufacturer. For a metal clamp-in stem that you are wanting to fit the Trailmanor, ask for a 'TR416 valve stem'. That says it all.
They make a TR416L, which is a longer (hence the L) version of the TR416. You don't want this one. I am not trying to confuse anyone, but you want to make sure you don't get the "L" version because it will stick out, where you might snag it on something. Now if you are the styling and profiling type, and have put hubcaps on your wheels, you may want the longer stem.
