Yep learned the rookie way myself. Bought a used MH and the salesguy pointed out "it even has the valve extenders for easy air checks"
Little did I realize all the wheels had rubber valve stems and the "extenders" were those cheap braided ones you see at the local autoparts stores and CW.
We were on a trip back East pulled off the FW into a little town to fuel up. I always do a walk around and even with my bad hearing I heard a hiss coming from the rear duals , bent down and sure enough the braided extender had the "rubber" valvestem tweeked over to the side and it had started to tear the rubber valvestem and was leaking air.
Found a Firestone truck tire shop a few blocks away and had them put metal valve stems on.
They didn't have any of the longer brass ones like mentioned above so had to put the braided extender ones back on.
Next up sold and bought another new to us MH, pulled another rookie stunt, when I had new tires put on I had them put all metal valve stems on,, on another post here I saw someone post up about the metal extenders (not the braided type) so I ordered up them... Yep another rookie mistake.
Being on a fixed income I didn't want to pay the money for the Tire Man ones..
Should of done it... One of the extenders I have to sit there and in about 5 minutes I can get just about 10 lbs of air pressure put in the one tire ;(
Read the post on tire pressure vs weight of MH and was adjusting the pressures.
Didn't like the ride so went back to the pressures I had ....
Spend the money and get the Tire Man ones !! In the long run IT IS WORTH IT ...