Whenever you say that something is “the key” to success, you immediately open yourself up to ridicule because you can always make the argument that something else is more important. You can soften it up by saying “a key” or “a major key,” but the bottom line is that a true “key” only works in one lock. You can't use just any key or a key that looks like the key. In order to open the lock, “the key” is necessary. So fire away if you disagree with me.
Inflate-through valve caps are the key to truck tire inflation pressure maintenance. Without them, the pressure never gets checked or adjusted because it's just too much of a hassle. Drivers will thump or kick every tire with a standard valve cap, and maintenance people will be tempted to do the same. No valve cap at all is a foolish option because the cap is technically the main seal. I can't say I totally understand it, but valve manufacturers maintain that the self-sealing cap is the primary sealing mechanism for the valve stem. Without it, the valve core is exposed, which often leads to a slow leak.
The first job of a valve cap is to seal the end of the valve stem and prevent air from escaping. A small rubber O-ring at the base of the cap is a sign that a valve cap is self-sealing. On truck tires, high brake temperatures require metal valve caps because the plastic versions usually melt on inner wheel positions, especially in the summer months. The second job of a valve cap is to protect the valve core from dirt and moisture. The “pin” on a valve core is connected to a tiny spring that allows air to enter the stem when depressed and prevent it from escaping when it's relaxed. If there is debris around the outside of the pin, an air pressure check or adjustment may result in an air leak when the foreign material prevents the core from closing completely. Standard metal valve caps have admirably protected cores for years, but they cannot support an effective tire inflation pressure maintenance program.
After 29 years in the tire business, I've come to the conclusion that most people are just lazy. We don't get up to answer the phone, change the channel, or adjust the speed on the ceiling fan. And I say “we” because that was probably me last night. If something can be automated to save me time, effort or money, sign me up. I'm embracing the digital age because it gives me more chances to be lazy. If I were a fleet executive in an ideal world, all of my inflation pressures would be checked at a gate reader so a loud siren would go off in the cab until the driver addressed the low tire situation. Of course, that's not possible without tire pressure monitoring sensors and since it could be decades before fleets go digital with their inflation pressure maintenance, the world still relies on the air gauge.
Notice I didn't say foot or tire club. The only way to know the air pressure is to use a gauge on the end of the stem. The inflate-through valve cap allows that to happen without the additional effort of removing and reinstalling the cap. It is a “no excuses” approach in every sense of the word because it doesn't take a lot of time to check the pressure with a gauge when the proper valve cap is installed. Without inflate-through valve caps on every valve stem, fleets cannot expect a tire inflation pressure maintenance program to succeed. People are just too lazy.
Kevin Rohlwing can be reached at [email protected]