Well I learned something. Running TT Truck with 4.40 by 23 tires on rear. Tire blew when the tube core stem blew out of the tube! Never knew how a tube was constructed like this! I have another thread asking for advice on the split rim wheel before I take it to a truck shop today Note machining on metal stem to grip?? the rubber???
A good truck tire shop can vulcanize a new stem in place. They will not likely be familiar with a split rim and may need your help.
Split rim, or split ring? They're often confused. If it's the latter, they probably will be familiar with it.
If your tube hasn't been ruined, you can install an original metal valve stem that was used when the truck left the factory. Simply find out what the size of that valve stem is, and find some. Next, follow the guidelines that have been posted on this forum many times, and you should be able to re-use that tube.