RV Tire Safety: Yes, you do need “bolt-in” metal valve stems with your TPMS

10

with RV tire expert Roger Marble

This is a comment I came across on a TPMS story on a Sprinter RV forum:

“My new tire pressure monitoring system just saved our just-completed trip to Florida. Thanks to you all I thought I had, and paid a lot, to Mercedes to replace my rubber valve stems and add metal valve extenders for my sensors. If you remember, I did see the front wheel valves Mercedes did NOT replace with steel. I did get BORG valve stems from ShinyRV.com, as suggested, for the front and my local repair shop installed them. I could not see into the rear duals to check.

“Well, you were right. After about 2000 miles into our trip, I turned on the TMPS to check pressures. The warning came up right away on one of the rear tires, 7 PSI. Sure enough, after five hours just off of interstate 75 in Florida, Mercedes had roadside assistance change to the spare (still have warranty). I added some air to the flat tire and soaped the rubber valve to verify that’s what caused the leak. It didn’t seem like a rub through but I did see cracks (must be from vibration).

“We drove 160 miles to a tire repair shop in Georgia. They put in small rubber valve stems in the spare and all four rear tires because I couldn’t trust the rubber valves. All TPM sensors were removed from the rear wheels. Lesson learned: TIRE PRESSURE MONITORING IS A MUST ALONG WITH STEEL VALVE STEMS. Rubber ones will crack and leak. I will order BORG steel valves for the rear wheels.”

I was a bit concerned about the comment on “turning on the TPMS” to check tire pressure, and I did offer a comment that you need the TPMS turned on for it to provide a warning.

I am posting this comment to point out what can happen when you use rubber valve stems and an external TPM sensor.

 

Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.

 ##RVT937

 

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Norval Chan
4 months ago

For those using rubber stems, why not just change to metal stems and eliminate a possible weak point? Is it worth the few $$$ to possibly have a stem fail at an inopportune time?

Craig Meldrum
6 months ago

The contention that TPMS systems have to use metal systems is a fallacy. Certainly some systems have sensors that are so heavy that using rubber valve stems may cause problems however I have personally run rubber valve stems with my TPMS system (InnoTechRV) for over 10 years and almost 70k miles with no problems at all.

David Kendall
6 months ago

Here’s a confirmation. TST specifically told me that their Cap Style TPMS monitoring sensors work on rubber valve stems. Sensors with a flow through port design require metal valves because they are longer and heavier.

David Kendall
6 months ago

I suggest that Roger research this opinion more (e.g., contact TST). I purchased a TPMS through TST (Truck System Technologies) and they recommend specific monitors for rubber tire stems. I towed my travel trailer 22,000 miles with those monitors with no problem. You should have short stems (common sense).

I also think metal stems would be stronger, but 5 pounds centrifugal force on a metal stem also adds stress.

HGoff
6 months ago

I agree with John T – i have a Tire Minder system on both my tow vehicle and trailer – rubber valve stems with no problem. As a professional engineer i just did a calc and determined the centrifugal force on the valve stem of my truck wheel going 60 MPH is 5 pounds. Also, this would be a constant force (toward the edge of the wheel) so it wouldn’t be moving much once the vehicle got up to speed.

i agree that metal stems would be better – but i’m not seeing where they are required

urban myth?

John T
6 months ago

This is opinion, not fact. I’ve towed 15,000 miles with the regular rubber stems on my TST-507s, and have never had a problem. I’m sure the vast majority of TPMS-equipped readers have the same result.

J J
6 months ago

I use TPMS on the toad as well but because Hyundai builds their TPMS sensor into the bottom of their valve stem I have no choice but to leave them rubber. I do remove the TPMS cap (0.6 ounce TST 507) once we arrive but really most of any damage will be done while towing at sustained high speed.

And better yet, I have no spare tire for this car nor does Hyundai have one available for their hybrids.

Bob
6 months ago

Same Q: as Will B. Also, why not rubber? Are they apt to fall or get knocked off? Is the weight of the sensors a problem, causing stem cracking? Could the problem with the leak be faulty, or damage caused by, the installation? Were they old before the installation? Many tire repair shops replace the valves whenever tires are unmounted. (The question is really, ‘WHY was this a problem when thousands of drivers use rubber ones all the time?’) And, why did the last repair facility remove the TPMS? Did they steal them, or have a reason, or give them back to you loose? Seems that keeping them on temporarily for immediate driving would be a good idea until the stems were replaced for just the reason you give. And, why did Mercedes not add metal stems to the front wheels? Was there a reason? You raise a lot of questions.

TB673
6 months ago
Reply to  Bob

The weight of the sensor IS the problem.Centrifugal force (when driving) coupled with the extra sensor weight flexes the valve stem.
The tire shop removed them so the same problem wouldn’t happen again.

Will B.
6 months ago

VERY confusing statement:
“They put in small rubber valve stems in the spare and all four rear tires because I couldn’t trust the rubber valves”