Hi Folks
Last year I ended up with one of my new trailer tires having a valve stem leak. So I took it in to NTB where I bought my Denman trailer tires from to put another new stem in. $22 later I left and out we go again. About 3 months later it starts again going flat. Pump it up and wait a few days then pump it again. That went on for about 4 months. OK it’s time to deal with this thing myself, I thought they must of left some rust or something in the valve stem hole.
Over the winter we didn’t camp much due to the weather. The leak was bad enough the tire would go almost flat after about 3 weeks. I didn’t want to crease the tire so I took it off and put the spare on. This winter I was also researching tire pressure monitoring systems and bead balancing. The TPM system would be the type that screws on the valve stems and they recommend that metal stems be used due to the increased weight as it fatigues the rubber stems, even high pressure rubber stems like I had. So I had the perfect need to fix this problematic valve stem, install a metal one, install balancing beads and do the other 4 tires. At $22 a tire x 5 to change stems I said, OK I’ll deal with this. Simple enough as I have mounted many tires over the years but all where rubber snap in stems.
I also researched out these T valve stems from Hawks Systems
TIRE PRESSURE MONITORING SYSTEM They offered a unique system that had 2 valve cores on them. This let’s you add or let out air and leave the TPM sensor still on the stem. So I order 6 of them to have a spare. They showed up in February. About 4 weeks later, 6 more show up…. It seems that had a problem internally with the valve core so they sent out new ones to replace the ones I had. Good thing I didn’t have them mounted already but they did good by their problems. Here is what they look like.
So the weather warmed up some and I pulled out my old tire changing machine. Doesn’t every RV’er have one? LOL. OK JohnB where the heck did you get a tire machine?? Well when I was in high school I use to help out at my step dad’s garage after school and the new kid on the totem pole learned how to change tires the modern way and pump gas. Back then there was no self serve…. He had an Esso station, later Exxon, when repair garages where privately owned and they bought gas and sold it. Gas prices would only change when a new tank load come. Guess things have changed a little bit in the gas sales area…. So he had this Atlas tire changing machine. As time went on my farming duties increased and so did college. He upgraded to a new machine but kept the old one. After 45 years in the garage business he sold out to a developer who wanted the land to build a Walmart. So the garage equipment went up for sale and for $50 bucks I got a tire machine. My step brother ended up with the tire balancer. Wish I would have had that too… This things weighs a ton, it all steel. It is at least 40 years old may even be 50. I have had it for 25 years…. So here it is and how it works.
HenryJ some how picked up I had one from this one picture from his balancing beads post. All you can see is the center stem of the machine in the middle of the wheel.
Here is the rest and how it works. It runs on compressed air.
You put the tire on top, an anti rotate pin goes up thru the lug holes.
Screw down a center hub that locks the rim to the machine.
The machine is made to break both the top and bottom tire beads at once. In my case I only wanted to break the valve stem side. These rim arms go in the machine to compress the top bead.
From the bottom the machine pushes up to break the tire bead
Once the beads are broke you can use the same machine to demount the tire from the wheel. There is a top mounted tool that has 2 ends, one for removing, one for installing.
Here you can take the tire off the rim
Here you can put it back on the rim
And the name plate
So if you happen to luck out and have one of these, doing tire work is not that bad. Now to the metal stems saga. What was suppose to be a fairly quick task didn’t turn out that way. Trailer wheels are really not the greatest for metal valve stems and it’s amazing rubber snap ins even work. At least in the size I have. The valve stem hole is punched in the rim during manufacturing and they form the rim after. The bends of the rim end up creating a non flat area for the valve stem hole. Snap in rubber stems are more forgiving for contoured rims where the stem hole is in the contour. Metal stems ideally need a flat surface to help give the main valve stem seal a chance to work which is the actual hole in the rim.
Here is the Hawk stems in a series of trials. I first started out with when they sent me as a configuration.
Here is the outside
The inside
Put the balancing beads in, put the tire on the ground to lay it flat and help push the tire up on the rim. I also have an inflation band, again old school but it gets the job done, that compresses the tire to help start the bead.
Since I was using DynaBeads for balancing they do not want a lot of bead lube up in the tire so you have to put the bead lube on by hand taking care to only use as needed. Bead lube is essential to have the tire slide into the wheel correctly during inflation and use lower seating pressures.
Wipe it on the bead by hand, not with the normal brush
Put the inflation band on and pump it up
As soon and the bead starts to catch on the rim you need to deflate the band and roll it off the OD of the tire. This is to prevent the tire from expanding it and never get it off… Just bleed it and roll it up on top.
Once you have some air in the tire and the bead started I switch from the quick filling air chuck to one I can read pressure on. You really do not want to go over 40 psi to set beads on this size tire. They pop bad enough at 20psi.
Once the bead is set, I pull out the valve stem, deflate, let the tire relax then air it up again to full pressure. That is if you do not have a leak from the get go. It did at about 30 psi, blowing like crazy on the valve stem. That is a little bit of water there you are seeing bubble. OK take it back off….
The 1st one I rolled the stem seal. My goof. So put a new one in
This one leak as bad just maybe 10 psi higher. OK off again….. But there is no roll at all. It just plain won’t seal.
OK what is going on here. Maybe the stem hole has issues. Well there in no rust or heavy scratches.
So I started calling around. 1st to Hawk. They where not much help. They told me take it to a tire shop. I asked what torque are the nuts suppose to be at to make a seal. He did not know and said he could email it to me. He said the tire shop would know…. So 2 days later he emailed me the torque and still said they recommend a tire shop install these.
Here is the “short” version of this saga… LOL
I did go to 5 tire shops and ended up with no more then I went in with. The tire shops around here never heard of a TPM system that screws on the valve stems. They all use the auto type that is inside the rim so they do not deal a lot with metal stems in trailer tires. They always put snap in rubber stems.
These Hawk type stems could work on a machined aluminum rim but odds are against you on trailer tires. Even regular metal valve stems have a lot of issues but I was able to get them to work.
Here is the problem. The rim hole.
You cannot get a flat sealing surface to pull even against. This is after I even added a double sealing washer.
I actually did get 1 to work. But after that I gave up and went to Napa and bought straight metal valve stems. They too have issues trying to seal in the curve. I added a top seal on the outside and these then worked right from the word go.
Here is what comes in a package along with an adapter for a 5/8 rim hole. I cut that down to make the outside gasket. As you can see here these do not sit true flat either.
Here it is compressed
And yup, it works out of the gate
I also use a little removable thread locker on the stem nut
Here are the rubber stems.
They don’t have a good sealing setup either but they conform better to the bends.
The primary pressure seal is the rim hole that is rough punched to start with. You can see here the Hawk gasket up in the hole from the bottom. That little bit of rubber is all that is sealing. On the rubber snap in stems the rubber flexes around the rim bend radius's. The Hawk never had a chance
You can see here the rubber stems is not even laying flat for the secondary seal to work. The secondary seal is the face of the rim.
I now have all 5 tires converted and 1 is a Hawk stem. They have all held pressure tight now for over 2 months and 3 camping trips. So hopefully the leaking tire saga is behind me.
Now I can get my TPM system. Looking at TST (Total Truck Systems)
Hope this helps someone in the future.
John
PS If you want more pics of the saga and process see
here
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