I was adding air to the motorhome tires (I love my Viair air compressor!) and was turning and turning the valve stem cap when I realized the cap wasn’t coming off. The stem itself was unscrewing! I figured it out just in the nick of time before I unscrewed the stem all the way. I hurriedly turned it back in, held the stem and got the cap off and added air.
Having had a valve stem come out while on the road, I knew just how bad it could get. It was lucky that when the valve stem blew off it was on an inside dually and not the front steer tire.
We didn’t have a tire pressure monitoring system (TPMS) at the time and the six-month-old tire was completely destroyed. About $800 later, we had a new tire and a battle getting the money back for the defective mounting. Once our persistence on our claim got high enough in the pecking order, Freightliner sent us a check.
The valve stem unscrewing incident made me think about articles I had seen by tire expert Roger Marble on RVtravel.com about valve stems and a valve stem tightening tool. I checked with Roger, and he told me that over-tightening a valve core can cause it to fail, so it’s best to use the little valve core tool. The nut on bolt-in metal stems only needs 25 to 45 inch-pounds, so a basic “snug” with a regular hand wrench is fine. Here’s a link on Amazon to a valve core tool that Roger recommends. It’s also available at auto parts stores.
##RVDT1667
So you expected Freightliner to pay for a tire you knowingly drove on flat. Why didn’t you call a tow service to come out and fix it?
Some motorhomes have both metal valve stems and metal valve stem extensions allowing access to the inner dual wheel from the outer wheel. It is possible to accidentally unscrew the valve stem extension and let the air out of your tire. That said, tightening the valve core with a core tool is far from the best way to tighten a loose valve stem extension.
Larger class A motorhomes have truck wheels. In many installations, the valve stem is metal and is mounted to the wheel using a retaining nut. If that nut is loose, attempting to unscrew the valve stem cap may unscrew the retaining nut instead. For those of us that have metal valve stems (not the rubber ones that are pressed into the wheel), check the nut at the base of the stem where it enters the wheel. It should be tight.
12 comments before someone with a clue shows up. About par for the course. People using an external TPMS sensor also commonly have metal valve stems installed on their trailer wheels.
you didn’t read the first paragraph, as he was adding air to his MOTORHOME NOT TRAILER!
Thank you, Michael. Glad you brought us some knowledge on this topic.
If the mounting nut is loose the tire will lose air as the seal is drawn tight against the inside of the wheel.
Add me to the list of … WTH is he talking about? Valve stems that I’M familiar with are rubber and are pushed/snapped into the rim from the inside. They don’t thread into anything.
I’m with the rest of the confused here, valve stem or valve core, one or the other not both.
Lost me between stem coming loose while turning cap and special tool for valve core. Anyone remember caps with core tool on it?
Yes
Yep have some still, they’re handy sometimes.
The confusion this article causes is due to the lack of pictures. SHOW the problem is better (and shorter) than describing it in words.
90% of the valve stems have plastic caps. I’ve never seen one seize to the stem.
What does a loose valve stem have to do with tightening the valve core other than trying to sell a tool on Amazon.
Have to agree w/Bob.
Some of you are mistaking the valve stem core for the valve stem. The author is describing the loosening of the valve stem, not the valve stem core.
That’s googles way of inserting an ad for the valve stem core tool.
I’ve managed to unscrew the extension on an inside dually when removing the cap, but agree with John’s comment about loosening the valve core.
You sir are on the right page, this was my first thought as to what he was describing. The multi-hundred thousand dollar motorhomes usually come standard with the extensions on the valve stems because checking/adding air to the inside dual requires a special tool not like your Walmart car tire pressure gauge.
Not sure I understand how a valve stem cap can unscrew the valve stem…there’s not connection between the two. What am I missing?
Same here. A bolt in valve stem goes in through the inside of the wheel with a nut on the outside. It might loosen itself from the nut by turning the cap or even the core, but I would think that would be very noticeable while doing it.
Yep