Get metal valve stems for your external tire pressure monitoring sensors
You want a full metal valve stem. We have had many rubber valve stems fail on us because the external TPMS is heavy and puts extra wear on the stem.
If your TPMS is brass, the valve stem should not be aluminum, because this can cause corrosion. Most valve stems on trucks or RVs will have a metal core that is brass, chrome, steel, or nickel. All of these should be fine to use with a brass TPMS sensor. Aluminum is usually only used on lighter duty wheels.