Paul in Houston TX wrote on Wed, 07 Dec 2016 12:13:43 -0600:

Some alloy wheels and all large trucks use the nut type.
They just unscrew, but they rarely need replacing unless obviously damaged.

Thanks for letting me know. I've never removed a tire valve before, so,
this is a first (I'm repairing a tire that has a hole in the middle of the
terad).