All are metal on 22.5s as far as I know. The small gaskets need to be changed even if the stems themselves are uncorroded,bent n holes or otherwise damaged plus the valves inside the stems themselves and the caps.
Only stainless steel or chromed stainless steel is acceptable. The caps themselves should be the best with the rubber gaskets inside.
The valve stem caps saved us once, on the left front wheel. The valve had been loosened and pressure was down but the cap kept most of the pressure in and if tighter it might have kept all in. The disaster awaiting from a blown low pressure hot tire makes the price worth while perhaps. The trend has been for shops to use the cheapest Chinese junk. Ask to see what they install and where it came from. Freightliner put on wheel nut covers that were loose and rusted in a few weeks from rain. They had barrels full of them they damaged our originals.Said that was all they had. Called Freightlner South Carolina. They had the American made stainless ones. They didn't want to pay for them and lied. hd them order the right ones.Caveat Emptor is the rule of the day.