[rotorwrench]

Inner tubes have sort of gone the way of breaker type ignition system components. There are less and less companies that manufacture these products in the western world and I don't know of any american company that does. I have the same problem with 16" tubes for motorcycles. I've been purchasing the Michelin brand tubes but they may be made in China as well. When a person googles for information, it's mostly Chinese sites that come up. Thailand, India, and Vietnam make a lot of rubber products too.

Tubes to fit 19" and 21" tires are likely all made in Asia. It's a niche market that won't generate kind of payback that major corporations want.