A year or so ago, I ordered the rear duelly valve extensions and had them installed when I bought new tires. The inner tire had a long straight valve stem that fit into a grommet (rubber stabilizers) in the outer rim hole.
However the valve stem from the outer tire itself did a 180 through the rim hole with no stabilizer.
I did have an issue a few months ago where the outer valve stem loosed from vibration and the tire went flat. I pulled that tire off, broke the bead, and tightened the nut holding the valve.
Last week I ordered two more stabilizers for the 2” hole and installed them today.
Since the stem is off-center and close to the edge of the hole in the rim, I had to modify the stabilizer with a utility knife.
Using a flat head screwdriver, I was able to install the stabilizer however I didn’t like that the stabilizer hole was now a slot.
Using some rubber cement, I was able to ram the piece I cut out back into the slot to give all around support for the stem.
Completed job with stabilizers on both stems.
As a footnote, if I had to do it again, I would try drilling a new hole near the edge and feeding the valve through the new hole.