Inside Dual Tire Leak

September 19, 2011, 09:21:37 am

Have had slow leaks from inside rear dual tire. Replaced valve core several times; no leaks in the tank but when going down the road the core begins to leak. Using 6" extensions with rubber boot to stabilize; Michelin XZA2 tires approximately three years old on 2003 36' U270. Any thoughts? Thank you. Joe Shirley

Re: Inside Dual Tire Leak

Reply #1 – September 19, 2011, 09:27:30 am

My experience with dual wheel tires, Simple, have a properly secured stem that is properly tightened, I do not use extensions, just the long stem type. When I purchased my 01 320, it also has slow leaks, I removed all six wheels, tightened the stems a few turns of the nut, made sure the valve core was properly snugged, solved the problems, now they hold air for months, even the PP seems happy, that is another story.
FWIW

Re: Inside Dual Tire Leak

Reply #2 – September 19, 2011, 09:35:39 am

So are mine....

best, paul

Quote

even the PP seems happy, that is another story.

Re: Inside Dual Tire Leak

Reply #3 – September 19, 2011, 09:50:33 am

Be very suspicious of the grommets for the valve stems.

I had similar symptoms on a steer tire on SOB. There were no leaks when parked. The tire lost pressure slowly while the coach was in motion. We pulled the tire, replaced the grommet on the valve stem. The tire never leaked again.

We were using TST TPMS. We had a more sudden failure on an outside rear later on the same trip. It was another grommet failure. We removed the TST and had no more tire failures in the brief period when we owned that coach. The tires, stems, and grommets were old. We sold the SOB, bought the Foretravel, put new tires on it, and no longer use TPMS. Other folk have been very pleased with TPMS.

Re: Inside Dual Tire Leak

Reply #4 – September 21, 2011, 12:08:26 am

Quote from: Joe Shirley – September 19, 2011, 09:21:37 am

Have had slow leaks from inside rear dual tire. Replaced valve core several times; no leaks in the tank but when going down the road the core begins to leak. Using 6" extensions with rubber boot to stabilize; Michelin XZA2 tires approximately three years old on 2003 36' U270. Any thoughts? Thank you. Joe Shirley

Joe,
This probably isn't what you want to hear, but I would guess that you will have to break the tire down and carefully inspect the tire stem nut, the tire and valve stem seating surfaces and the inside of the tire, if exterior soaping won't produce a bubble.
I put on (6) new Michelin tires ( XZA3 275/80R 22.5 14ply LRG) and all new Alcoa valve stems in July of this year. Each tire seating surface and each stem seating surface was cleaned and buffed during the tire changeover.
From the very first day of installation, the street-side outer dual presented an inconsistent, slow leak. The other (5) new tires behaved normally and were checked frequently via Pressure Pro readout.
I took the Pressure Pro sensor off the leaking wheel (to eliminate it as a possible cause of the leak), and used a strong soapy solution to look for tread or stem leaks (nothing). I took off the stem nut, checked the stem recess with soapy solution (nothing), inspected the nut carefully, reinstalled and properly torqued it. The tire would sometimes hold pressure for days. Then, after driving the coach, it would lose as much as 5 psig each day for several days.
My son took the wheel and tire off the coach and we thoroughly soap tested everything (nothing). We changed the valve core, just to do something (lost 6 psig that night).
So then I went back to the tire dealer that did the installation in July. They did the same soap testing that my son and I had done the day before (nothing). Then they put it in a tank for 30 minutes (never a bubble). They broke down the tire and changed the valve stem and the valve core because, after lowering the pressure from the110 psig test pressure to 95 psig (that I normally carry), the valve core presented a continuous bubbling. The theory was that the the valve stem and/or core was marginal and was inconsistently seating after checking the tire pressure. I think that the tech got the new and old valve stem nuts confused (reversed) at this juncture. You will see why later on. The tire lost eight psig overnight that night.
Back to the tire dealer the next day. Soap and tank again to no avail. The tire dealer had confidence in the rim and stem but not the tire. The Michelin Rep had said, break the tire down again and more carefully inspect the tire stem nut, the tire and stem seating surfaces and the inside of the tire.
This time, under closer inspection, it was discovered that the tire stem nut had a hairline fracture. It could not be seen while on the rim and was barely detectable with the naked eye. It was obvious under a magnifying glass. I believe that the stem nut may have been overtightened and fractured back in July. Nothing else was found to be remarkable at all.
Now, to me, the stem nut is outside of the pressure boundary, and I didn't have any confidence that this would resolve the mystery.
But, VOILA! We were two days late in arriving at the North Atlantic Fall Rally in Plattekill, NY, but the tire is no longer out of step with its brethren. It has responded normally to all environmental and driving changes and we're now in Ohio Amish country (Holmes County) with no leak. Talking it over with other FT'ers at the rally, one FT'er (truck fleet owner), like the Michelin Rep., had seen this before. They say that the Alcoa rim stresses fluctuate enough, throughout each load-bearing revolution, that a fractured stem nut can lead to minute, inconsistent leakage depending on where the valve stem is located when the coach is parked. Located at the top of the wheel, while parked, a fractured stem nut may cause a slight leak whereas located at the bottom it may not. Therefore soap testing may be very difficult. And take the load stresses off the wheel (by taking the wheel off the coach) and it may not present a bubble, even when submerged.
The tiny leaks are the worst! And the most frustrating!
Anyway, I thought that this was strange enough that it might be worthwhile mentioning on the forum.
Maybe others can benefit from this learning experience!
As usual, FWIW
Neal

Re: Inside Dual Tire Leak

Reply #5 – September 21, 2011, 08:25:38 am

And I thought the weird stuff only happened to ME!

Re: Inside Dual Tire Leak

Reply #6 – September 26, 2011, 06:24:59 am

Neal; thank you for your post. The narrative you contributed is very helpful since your experience mirrors ours. Time for a magnifying glass inspection!

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