Originally Posted by CWtheMan
Hundreds of millions of snap-in valve stems are used worldwide on a large verity of applications. They are inexpensive, reliable and easy to install. And they meet industry requirements.
There are advantages and disadvantages for any application. I always used metal valve stems on the wheels on my 6000# axles. For me the advantage was obvious, itís easier to check and service the tires with mobile compressors. And, like other designs the metal ones fail internally and I replace them whenever I replace a tire.
Let the situation dictate the use of metal valve stems. Youíll be a better friend with Schrader and others.
Yes "hundreds of millions of snap-in rubber stems" with few problems but the vast majority did not have a TPMS sensor hanging on the end of the stem. There are a number of variables such as the angle for the stem hole that can affect the level of movement when a TPM sensor is screwed on the end of the stem. There are a number of different stem lengths that will also affect the lever effect and the torque applied to the stem.
Based on my 40 years experience with tire valves and my 18 years experience with TPM systems I recommend that anyone running an external TPM sensor use bolt in metal stems when adding a TPMS to their trailer application. Just switching to the "Hi-Pressure" Snap-in stems will not eliminate the flexing problem.
Sometimes strict adherence to some 50 year old industry guideline is not always the best practice, especially considering the resistance to change seen from those organizations.
Too often political pressure inhibits changes for the better. Look at how long it took for RVIA to adopt the +10% reserve load capacity over the objection of some RV companies. DOT still has no Reserve Load requirement and still limits the TPMS requirement to vehicles with 10,000 GVWR or less as if a 10,100 GVWR vehicle can not suffer tire failure due to loss of air.
I am also curious with your observation "the metal stems fail internally". I have never seen a metal stem fail if not involved with some external accident. What "internal" part have you had fail? We can't be talking about the valve core as those parts are identical in cheap rubber snap-in stems or Hi-Pressure snap in stems and metal stems used in everything from wheel barrows to HD over the highway trucks. If you can provide data I will gladly change my position.