with RV tire expert Roger Marble
Here’s my opinion on the ongoing discussion regarding what valve stem to use with an external tire pressure monitoring system (TPMS) sensor.
A standard 65 psi max, rubber valve stem is very flexible, as seen here:
Some people think the 80 psi max “High Pressure” HP 600 rubber valve stem is OK to use with external TPMS sensors, but you can see the HP 600 is still flexible:
Here is proof that an HP rubber stem can fail when a TPMS sensor is installed:
IMO, staying with any “snap-in”-type stem is false economy given the metal bolt-in stems only cost $3 to $4 each. Not all tire stores will have the metal valve stems so check first. If they don’t have them, you can get stems at AutoZone, O’Reilly Auto Parts, Advance Auto Parts, NAPA Auto Parts, or most any auto parts store or even on Amazon.
They are easy to install, too. Don’t let the service center tell you installing metal stems is a lot of work. Watch and you will see:
Read more from Roger Marble on his blog at RVtiresafety.net or on RVtravel.com.
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Just wondering, how many RVers, have a bead breaker, to
I provided the video to show that the job was not difficult. With equipment (tire changer) should be less than a couple minutes each if just installing bolt in valves. So don’t get ripped off by a tire dealer who doesn’t want to do the job. Harbor Freight sells a “bead breaker” for $50 if you want to do the job yourself. No need to take tire off the wheel and only need to “de-seat” one side so no re-balance needed either.
i installed TPMS on rubber valve stems before I knew about the metal ones. After a few thousand miles the rubber cracked and leaked. Fortunately the tpms alarmed for a fast leak in time for me to get to a safe place to change tires. After a nervous two hour trip home hoping the other three valve stem would hold, I put in metal valve stems and have had no further problems.
Hate to disagree however I have run high pressure valve stems on my 2006 Saturn Vue for 10 years now without any failures. I use Tire SafeGuard CAP sensors not the flow through ones that would require even sturdier valve stems as those sensors or larger and heavier.
Glad to hear you have not had any problems with your HP stems. A couple of things that can impact potential failure is the weight of the TMP sensor. Another is the angle of the hole in the wheel. Valves that are pointed directly toward the center of the wheel hub will have less bending force. Another variable is the temperature where you live and travel. People in warmer climates are more likely to have problems with both tires and valve stems because temperature has a big impact on the life of rubber components. This blog post talks about tire “age” but the information on temperature effect applies to all rubber parts.
Thanks Roger. That makes perfect sense.
Here’s a tip from someone who has changed, literally, thousands of tires. Get out all of your tools before you start. You will need:
Hydraulic floor jack to lift vehicle,jack stand or stands, impact wrench with extension and socket, torque stick or torque wrench, wheel stand with bead breaker, socket and ratchet for new valve stem, ratchet strap to help re-seat bead, bead sealer, wire brush to clean the rust, decent tire gauge. Not that $1.00 item hanging next to the cash register.
Better yet, the phone number of a reputable tire shop, where you can drop off the RV and go grab a lunch.
On a serious note. If you do change valve stems, DO NOT use metal caps. If the stem comes with metal caps, just see how far you can throw them and use simple plastic caps that will not corrode and refuse to unscrew from the stem. I have seen many stems destroyed by the fancy metal caps.
Usually corrosion of the metal cap to the stem occurs when the stem is aluminum as in many OE TPMS that come on cars and the use of some fancy aftermarket cap. The bolt in metal stems are nickle or chrome plated brass and the metal caps are also nickle plated brass so I do not see how they would corrode. If people are running external TPM sensors there is no need for a “cap” as the TPM sensor serves the primary purpose of keeping dirt out of the valve core chamber. If you do not run a TPMS (I don’t know why you would not) then in addition to keeping dirt out of the valve core chamber you also would want to keep air in the tire in case the core develops a leak. Cheap plastic caps are less likely to retain high pressure seen in tires under operation.
I use a very small amount of Anti-Seize on the stem threads to minimize the corrosion between the different metals, stem versus TPMS sensor.
How do you handle putting RV-type TPMS sensors on a car being towed to reduce the risk of the safety system causing the failure you’re trying to prevent? All factory car TPMS sensors I’ve seen have the car’s sensor built into the bottom of the rubber valve stem so you cannot just replace the factory valve stem with a metal stem without disabling the car’s own system.
I install the cap sensors on the towed car before we leave on a trip and remove them at the destination to minimize the risk. The larger wheels on a towed car also reduces the rotational velocity somewhat as compared to a smaller trailer wheel but a risk is still present. My TST 507 cap sensors supposedly weigh 0.6 ounces each but that’s still a weight on the end of a rubber lever.
I can only suggest you select the lightest weight TPM sensor. This may mean not using the extra “sensor lock” system that adds weight. Keep a close watch on the rubber stem. While I cannot check every possible OE TPMS design I think that some have a longer brass center to the stem so there is less flex of the rubber part because the bottom of the stem screws into the TPM module inside the tire which would decrease the flexing.