I know this has been discussed in years past, but can’t find the details right now.  Had a right main go down on landing today.  Closed runway, but luckily the FBO had a dolly and jack handy.  Anyway, every time I do the mains, I can never seem to find the right tube.  I always end up with the straight valve that is then preloaded by the bearing cover.  I think that is what caused my flat today... So, I’ve read the threads on whose tube to buy, but it seems that the bent stems are rare.  Th