replying to _, fyiman wrote:
According to this page:
http://www.sheldonbrown.com/gloss_sa-o.html

The external threaded part of a Schrader valve is 0.302" x 32
Threads-per-inch.

19/64" is about 0.297" (0.296875") which is a little smaller than 0.302".
5/16" is 0.3125" which is a little bigger than 0.302".
0.302 inch is about: 7.67mm (7.6708mm).
7.7mm is about: 0.303 inch (0.30314 inch)

For a tap, 5/16-32 (if that is standard) would probably fit close enough.

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for full context, visit https://www.polytechforum.com/metalw...tap-98941-.htm