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Valve Stem Vitals

Posted in How To: Wheels Tires on February 16, 2017 Comment (0)
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Tire tread is really the only contact to terra firma that we have in our vehicles, so choice of rubber compound, carcass design and tread pattern play a big part in off-road performance. However, it’s often the weak links that can bring us to a halt. Valve stems seem like such small, insignificant items and in most cases we’ll rarely give them a second thought. However, over the years we have seen a number of them get torn or broken off wheels so it may be beneficial to pay a bit of attention to them.

Standard rubber valve stems can be torn or damaged from debris entering the wheel and contacting the stem. While they can take a fair bit of punishment they are more likely to fail as the rubber ages. Rubber is more likely to flex upon impact versus a solid metal stem which may crack or shear off. Flush mount valve stems are available but are less convenient in use as they require a detachable stem that could be lost.

The risk of hazard to a valve stem can depend on the type of stem used but also its location on the wheel. If you’re considering new wheels and off-road reliability is a high priority, you may want to make note of where the stems mount on the wheels. Are they very close to the wheel edge or tucked back (or recessed) to offer better protection off-road? Valve stems sitting behind wider beadlock rings are often well protected but short stems there may be difficult to get an air chuck on.

The best defense is to avoid tire flat vulnerabilities ahead of time, but inevitably you’ll still encounter problems if you spend enough time in the dirt. Depending on your rig, you may or may not carry a spare tire, but having some way to replace valve stems can be a good plan should one fail. The usual way is to replace the stem from the inside of the wheel which is accessed by partially breaking the tire bead off the wheel, allowing you to reach inside to insert a new stem.

There have been a few tools that allow insertion of the rubber stems from the outside of the wheel using a compression cone to squeeze them in. We once clumsily pushed one in as a replacement working diligently for a good number of minutes with a screwdriver, but only after destroying the first two we tried to install. Colby Valve (colbyvalve.com) now offers their Emergency Tire Valve System. It’s a specialty valve stem that inserts from the outside and uses a rubber piece that is compressed to seal the valve to the wheel. We now carry one of these to replace a damaged valve stem should one occur.

You can often choose to use slip-in rubber or bolt-in metal valve stems. We typically prefer the rubber ones, without using the chrome outer covers, as they seem to be the most forgiving towards breakage when impacted by rocks or other debris. We also try to install the shortest ones possible that still allow us to fully access the valve stem with an air chuck. If you have factory or aftermarket tire pressure monitor sensors (TPMS) they’ll typically have a metal stem with some type of metal retention nut on the outside of the wheel. You’ll have to decide whether to keep them or swap to another valve stem type of preference.
Got a ripped or otherwise damaged stem and don’t want to break down the tire bead to insert a new stem from inside the tire? We found what seems to be a quick, solid solution in the Colby Emergency Tire Valve System. It’s a replacement stem that slips into the valve stem hole in the wheel from the outside as shown here on this cutaway wheel. Once inserted, a wing nut is tightened to pull a tapered brass fitting up into a rubber seal that flares and makes an airtight mate to the wheel. Installation is quick and easy without dismounting or debeading the tire. The valve shown on the right is their emergency valve with the wing nut. On the left is their permanent valve version that installs using a brass fitting and hex nut to secure the valve to the wheel.
On rigs that see a combination of highway and trail time where we air up and down on a regular basis, we sometimes add a second valve stem 180 degrees from the original valve stem. However, for the second stem we use a two-piece tractor or grader stem. These come straight or angled, and have a stem core that can be pulled to expose a large orifice which releases the air very rapidly. Whenever we go to air down using these valves there’s almost always someone commenting about the loud air escape as if we just jabbed our camping knife into a tire sidewall. Simply put, these things get the air out fast. And in our experience we’ve not had one leak at the added o-ring-sealed fitting. They do require drilling a 5/8-inch hole somewhere on your wheel to add the stem, but that’s a pretty simple process.

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