I finally got around to installing a new Hawkshead TPMS a few weeks ago just days before we left for a 17 day 800 mile camping trip. We are using Hawkhead T-valves which allow air to be added without removing the sensors. Our rims are alloy.I had the valve stems installed by a large well-known nnational tire company. They said they could not install the rubber grommets that came with the valve stems on the outside so they installed them on the inside of the rim. They said they do this sometimes if it won't fit on the outside. I wasn't sure about this so I called the Hawkshead distributor who said they are meant to go on the outside.Then doing some reading on the internet, it seems like it is better to have the grommets installed on the inside because the internal air pressure forces a seal against the metal rim.Is there a right and wrong way to install the grommets or does it matter? After 800 miles, the TT tires held the air just fine. Hawkshead said that their T-valve grommets should fit on the outside of most RV rims. Maybe the tire shop didn't take enough time and care to fit them correctly?Another question is that the inside surface of the rim has a round surface but the valve stems came with a flat washer. Should a convex washer be used? Where would I find them?

I had the valve stems installed by a large well-known nnational tire company. They said they could not install the rubber grommets that came with the valve stems on the outside so they installed them on the inside of the rim.Need to tell us what exactly you have... Direct or indirect... Model#...

myredracer wrote: ....it seems like it is better to have the grommets installed on the inside because the internal air pressure forces a seal against the metal rim.How mine are installed. It makes sense to me that the rubber washer is inside the wheel, protected from UV, and where the air pressure is pushing it to seal, vs having it on the outside where the air pressure is working against it pushing it to leak.I never questioned the tires guys (also large national chain) when they installed them this way, it just seemed logical. I think you get enough compression on the ol' flat washer to make a seal so that a convex washer isn't needed.myredracer wrote:After 800 miles, the TT tires held the air just fine. Bottom line, that's what you're looking for. I wouldn't over think it. You know the old saying, if it ain't broke, don't fock with it....

lawrosa wrote:I had the valve stems installed by a large well-known nnational tire company. They said they could not install the rubber grommets that came with the valve stems on the outside so they installed them on the inside of the rim.Need to tell us what exactly you have... Direct or indirect... Model#... This is what we have: T-valves What's confusing this is that Hawkshead says the grommet should be on the outside.

OK that's interesting....typical metal valve stems mount from the inside and the locknut goes on the outside. Are the sensors that hard to remove that you need this valve configuration?I'll stick by my original comment, if it ain't leaking.....

BurbMan wrote:OK that's interesting....typical metal valve stems mount from the inside and the locknut goes on the outside. Are the sensors that hard to remove that you need this valve configuration?I'll stick by my original comment, if it ain't leaking.....I agree if it's not leaking. But, I am picturing the little grommet on a curved surface being flattened by a flat/dished washer and am not sure if they will stay leak-free in the long-term? I came across a post by JBarca from a few years ago where he had trouble. Interestingly, he was trying to use the same valve stems. He found some valve stem grommets at NAPA that were thicker and had more to cushion when tightened up. The tire shop said they would re&re the valve stems for free if I thought it wasn't right so I *might* consider the NAPA grommets.Removing the sensors is easy. Not sure if I have an answer as I'm new to a TPMS. Seems like the benefit is not having to bother with resetting the monitor if a sensor is removed? I've also got the little locking things on them to prevent theft.Despite what Hawkshead says, I'm going to go with the grommets on the inside. I was wondering if there was a washer available that is concave in one direction to accommodate the curve on the rim surface but I haven't found one.

Correct way to install metal valve stems? | Good Sam Community

lawrosa
Explorer
Aug 21, 2014
I had the valve stems installed by a large well-known nnational tire company. They said they could not install the rubber grommets that came with the valve stems on the outside so they installed them on the inside of the rim.

Need to tell us what exactly you have... Direct or indirect... Model#...
BurbMan
Explorer II
Aug 21, 2014
myredracer wrote:
....it seems like it is better to have the grommets installed on the inside because the internal air pressure forces a seal against the metal rim.

How mine are installed. It makes sense to me that the rubber washer is inside the wheel, protected from UV, and where the air pressure is pushing it to seal, vs having it on the outside where the air pressure is working against it pushing it to leak.

I never questioned the tires guys (also large national chain) when they installed them this way, it just seemed logical. I think you get enough compression on the ol' flat washer to make a seal so that a convex washer isn't needed.

myredracer wrote:
After 800 miles, the TT tires held the air just fine.

Bottom line, that's what you're looking for. I wouldn't over think it. You know the old saying, if it ain't broke, don't fock with it....
myredracer
Explorer II
Aug 21, 2014
lawrosa wrote:
I had the valve stems installed by a large well-known nnational tire company. They said they could not install the rubber grommets that came with the valve stems on the outside so they installed them on the inside of the rim.

Need to tell us what exactly you have... Direct or indirect... Model#...

This is what we have: T-valves What's confusing this is that Hawkshead says the grommet should be on the outside.
BurbMan
Explorer II
Aug 22, 2014
OK that's interesting....typical metal valve stems mount from the inside and the locknut goes on the outside. Are the sensors that hard to remove that you need this valve configuration?

I'll stick by my original comment, if it ain't leaking.....
myredracer
Explorer II
Aug 22, 2014
BurbMan wrote:
OK that's interesting....typical metal valve stems mount from the inside and the locknut goes on the outside. Are the sensors that hard to remove that you need this valve configuration?

I'll stick by my original comment, if it ain't leaking.....

I agree if it's not leaking. But, I am picturing the little grommet on a curved surface being flattened by a flat/dished washer and am not sure if they will stay leak-free in the long-term? I came across a post by JBarca from a few years ago where he had trouble. Interestingly, he was trying to use the same valve stems. He found some valve stem grommets at NAPA that were thicker and had more to cushion when tightened up. The tire shop said they would re&re the valve stems for free if I thought it wasn't right so I *might* consider the NAPA grommets.

Removing the sensors is easy. Not sure if I have an answer as I'm new to a TPMS. Seems like the benefit is not having to bother with resetting the monitor if a sensor is removed? I've also got the little locking things on them to prevent theft.

Despite what Hawkshead says, I'm going to go with the grommets on the inside. I was wondering if there was a washer available that is concave in one direction to accommodate the curve on the rim surface but I haven't found one.
Harvard
Explorer
Aug 22, 2014
My take on this, if the grommet is on the inside then the grommet needs to ALSO stop leakage via the threads. If the grommet is on the outside then there is no issue with leakage getting by the threads. IMO.
BurbMan
Explorer II
Aug 22, 2014
Harvard wrote:
My take on this, if the grommet is on the inside then the grommet needs to ALSO stop leakage via the threads. If the grommet is on the outside then there is no issue with leakage getting by the threads. IMO.

Good point. A typical steel valve stem has the nut on the outside so the sealing washer goes on the inside. These stems are reversed with the nut on the inside, so it would make sense that the washer goes on the outside....
myredracer
Explorer II
Aug 22, 2014
Maybe there's no right way? Many sources on the internet say the inside is better because the internal air pressure forces the grommet material against all the metal surfaces. I wonder if one on the inside and also the outside would be better??
j-d
Explorer II
Aug 22, 2014
Perhaps indirectly related, the custom brass stems for motorhome wheels (the ones form TireMan and Borg, there may be others) install with the nut on the inside. They want Blue Loctite on the nut threads. I don't think it's for sealing, but because once the tire is mounted no way to tighten the nut. Were it to work loose, that is. Can be done when nut is on the outside. My take on the Loctite is that it prevents the nut working loose (as opposed to sealing the threads against an air leak).
Harvard
Explorer
Aug 23, 2014
Short term, I would bubble test. If they go low in pressure over long term you will know why.

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