I have some old HRE wheels, and one has a broken valve stem. The shaft of the stem is about 3/16 inch, or 5 mm, with a nut on either side of the wheel.

No tire shop around here can get me anything close.

I've tried HRE, and they tell me these are not available anymore, but they can get me some 8 mm stems.

Does anyone know a source for the smaller stems?