Duals losing air followup

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pheasant16

Well-known member
Joined
Jun 6, 2023
Posts
76
Location
ND
Last spring went to get class C out of storage. All 4 duals were flat. Lots of folks in the forum felt maybe some mischievous malingerers
had gotten over the fence and were playing. Filled 'em up and went about life. Never lost a pound from early May until I checked today.
One looked a little soft.( they all had 80#) 2 weeks ago last trip. We've had 9" of snow and lots of teens for temps the last couple weeks.
One had 6, another 68, another 45, and last 62. OK. It's been at the house, no gremlins here.
So anyway, wasn't mischief. Never seen anything like this before.:(
 
Valve stems, valves, extensions should all be suspect. Less suspect are the wheels themselves, they can leak too. This is all assuming you don't have a slow leak in a tire.
 
Hey an idea! All I get when I go to the tire shops around here is the deer in the headlights stare. Can't hurt. Will talk to commercial guys next week before we store it about replacing valve stems. Just goes to show geezers knowledge is invaluable
 
Kind of ruled out a bead leak as it was all tires, not just 1. If we replace stems and extensions that would kill that bird at the same time
 
If you replace the stems, and you use the rubber/brass ones, make sure they are the High Pressure variety and not regular passenger car stems.

This is a "high pressure" stem, rated to 80 psi. Lots of brass showing.

e-600-d.jpg


This is passenger car stem, only brass is the threads, rated to 65 psi

t-14-r.jpg


Charles
 
pheasant16 said:
Hey an idea! All I get when I go to the tire shops around here is the deer in the headlights stare. Can't hurt. Will talk to commercial guys next week before we store it about replacing valve stems. Just goes to show geezers knowledge is invaluable
Click to expand...

If you replace the valve stems... Consider Dually Valves... IF they have them for your vehicle they are WAY and I mean WAY easier to Fill Check as they are long and "Bent" so you access both inner and outer duals from the outside. A major improvement on "Standard" And all metal as well.
 
Found a commercial tire center that didn't give the deer in the headlights stare. Will take it in next week to see what they come up with. Hope they will stay inflated until I get it over. Thanks for all the ideas
 
Some of that pressure drop is probably temperature related - a 10 degree (F) difference on an 80 psi tire will lower (or raise) the psi about 1.5 lbs. You need to [roughly] normalize for temperature difference when comparing if the ambient is more than 6-8 degrees different fall vs winter or spring. The change in psi is 1.8% for every 10 degrees F.

Since the difference you observed is maybe more than just temperature, there seems there may be some actual loss. The mystery is why it happens when parked but apparently not during the summer when in use. A leaky tire bead typically leaks MORE when the vehicle is being driven and the tire flexes a lot. Ditto for a small puncture. And a leaky valve leaks independent of tire motion or position. I don't know of anything that makes a tire leak more when sitting unused than when being driven.
 
pheasant16 said:
Hey an idea! All I get when I go to the tire shops around here is the deer in the headlights stare. Can't hurt. Will talk to commercial guys next week before we store it about replacing valve stems. Just goes to show geezers knowledge is invaluable
Click to expand...
My life improved remarkably when I had pitaless rigid steel valve stems installed on all my MH tires.
 
Tulecreeper said:
I only know one definition for the acronym PITA. Adding "less" as a suffix is kind of original.
Click to expand...
Necessity is the mother of invention. Anyone who has spent an hour monkey a**ing around with those flexible stems trying to get air into the tire will know exactly what I mean. It was a chore just to check the tire pressure, you needed three hands. Now it takes 5 or 10 minutes and you're good. Flexible stems should be against the law punishable by lethal injection.
 
OK Guys. Tires were fine. Beads were good. The stems were replaced with longer ones, and the extensions were taken off and thrown away. Shop said the extensions are the problem. Was cold the day I went to get it, couldn't see the stems, asked how to check pressure. He cheerfully said we're here 6 days a week 10 hours a day. Fingers crossed.
 
Buy yourself a couple of these:
truck and RV tire pressure gauge
And make sure that the tire shop shows you where the stems are, and learn how to use the gauges.
When you're on the road, check the pressure often. (Once a day isn't too often. I check my tires every time I stop for fuel, and every morning before we head out.)
You'll find that there will be minor variances during the day.
 
I don't like extensions, nor do I like the Borg metal stems that the RV community is so crazy about. I attempted to install a set on my Sprinter wheels (special made for the Sprinter), and they didn't fit worth a flip, either where they fit in the hole in the rim or where they came thru the outer rim. I did one side and found how difficult it was to install the outer wheel without damaging the stem of the inner wheel and took them back to the tire shop and we removed them and sent them back.

I removed the stainless wheel simulators (still have them, even the buyer of the motor home didn't want them) and cleaned the rims and painted them silver to match the original MB silver, and installed plastic MB hubcaps on the front and painted the rear hubs black and used a straight/reverse angle tire gauge and Milton 12 inch chuck to service them. I carried all the stuff with me and never had an issue.

Charles
 
Last edited:
pheasant16 said:
OK Guys. Tires were fine. Beads were good. The stems were replaced with longer ones, and the extensions were taken off and thrown away. Shop said the extensions are the problem. Was cold the day I went to get it, couldn't see the stems, asked how to check pressure. He cheerfully said we're here 6 days a week 10 hours a day. Fingers crossed.
Click to expand...
It's too late now but one piece accessible steel stems should have been installed which would have enabled you to check the psi from outside the dually's. Not doing you much good if the tire shop is open and you're 6 States away.
 
pheasant16 said:
OK Guys. Tires were fine. Beads were good. The stems were replaced with longer ones, and the extensions were taken off and thrown away. Shop said the extensions are the problem. Was cold the day I went to get it, couldn't see the stems, asked how to check pressure. He cheerfully said we're here 6 days a week 10 hours a day. Fingers crossed.
Click to expand...
IMO metal extensions, not the cursed flexible kind, are fine as long as they are secured to the outer wheel so they cannot move or vibrate. Screwed down is best but a friend zip ties them down and has never had a problem. White/clear zip ties of course. Roadkill Garage insists black zip ties gives zip ties a bad reputation :)
 
IF properly installed, Flex Xtenders can be fine. I would never use them, myself. But, that is just personal opinion.

First stop when taking the Dancer home was at GCR Tire, where I put new shoes on the beastie, and had them install metal long stems on the rear inside rims.
 
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