Hard core hardware

Like Rodney Dangerfield, the tire valve stem just doesn’t seem to get any respect. It’s a piece of hardware that’s usually taken for granted and shopped for on price. Heck, it’s not like they’re really doing anything important –other than providing a channel through which tires are inflated and deflated and keeping the air in the tire.

Because people look for low-priced stems, it makes the number of cheap offshore valves coming to North America all the more astonishing. Their quality is all over the place, and can vary from shipment to shipment. Many are substandard, often only lasting a few months before leaking. With no name or marking on these valves stems, there is no traceability and nowhere to turn when problems arise.

So how do you ensure you’ve got the right, high-quality valve stem?

First, talk to your tire valve supplier about the product he sells. Ask questions about the valve stem’s expected life, how often it should be changed, what makes it better than other manufacturers’ valve stems, etc. Look for the TR (Tire and Rim) number on the valve stem. This is essentially a part number assigned by the Tire and Rim Association. Although this number does not guarantee a high level of quality, the manufacturer should be making valves in accordance with SAE material standards and Tire and Rim dimensions.

Also look for the manufacturer’s name or trademark, part number, and country of origin. Not all manufacturers put this information on the valve stem. But the more information you see, the more certain you can be that the maker will stand behind its product. And at least you’ll know whom to contact if there is a problem with the valve stem.

Next, select the right one. Valve stems have a nasty habit of looking a lot alike. Make sure the valve stems you select for your truck tires are high-pressure valves that can handle pressures up to 155 psi.

Truck valves come in two basic dimensions: the .625-inch rim hole width for steel wheels and the 9.7-mm rim hole for aluminum wheels. Most tire valves are corrosion-resistant brass, which can be alloyed for ease of machining and can easily be bent to facilitate servicing. Brass adheres to rubber fairly easily and high-pressure valves need good rubber-to-metal adhesion to keep the grommet attached.

The TR570 series clamp-in style valves are commonly used in heavy-duty truck applications. These can be bent to provide needed clearance from the brake drum. Make sure you use the proper equipment to bend them, or you can purchase them already bent. Due to the proximity to the brakes, heat can be an issue, so use grommets with high heat resistance. Some people think red grommets are better than black grommets for this application. But not all red grommets are heat-resistant, and the price for them can be double that of heat-resistant black grommets.

Aluminum wheels are where the 9.7-mm tire valves are used. When used in aluminum wheels, they must be plated. Alcoa recommends that a little Freylube be used around the valve stem hole to prevent corrosion around the grommet, which can squeeze it and cause leaks. Take care when installing these stems. They use an O-ring instead of a grommet. If the O-ring gets nicked or damaged during installation, the valve stem will leak. If you use metal truck valve extensions with your aluminum wheels to make the valve stem more accessible, use an extension stabilizer to protect the valve stem. It will also eliminate loosening of the valve stem nut caused by vibration.

The valve stem is only one part in a total package that maintains the air integrity in a tire. The valve core and the valve cap are equally important.

The valve core is the paramount seal of the valve assembly. It must perform in a wide range of temperatures and pressures and still seal the air channel. When spec’ing valve cores, always spec for high temperature. The type of service the valve core is made for is indicated by the seal colour on the core. A red seal indicates high temperature use, a blue seal is for air conditioning, and a core with a green seal is to be used with hydro-fluorides. Make sure you get the ones with the red seals.

Valve cores must be clean to ensure an airtight seal, so store them in a box and not loose in a dirty environment. Installing them too tight in a valve stem will damage the core and create a problem. They should be tightened to between 1.5 and 3 inch-pounds of torque. In case you don’t have a “Barbie”-sized torque wrench, this equates to hand tight. (Snap-On does make a tool, though, that measures inch-pounds if you feel the need to add one to your tool collection.)

Tire valve caps provide the final seal to the valve stem assembly and prevent contamination of the valve core. Not all caps are created equal and you should be aware of the differences. First of all, there are sealing vs. non-sealing valve caps. Black plastic caps are non-sealing and should not be used once the valve stem is installed in a tire/wheel assembly. Metal valve caps provide a good quality seal and high heat resistance can be spec’d as well.

Gaining in popularity are double seal or inflate-thru valve caps that provide two seals. They allow the use of inflation gauges and air-line chucks without removing the cap. This saves an enormous amount of time when doing fleet surveys and yard checks. (I think they should be mandatory if you’ve got aluminum wheels since removing the valve cap on inside aluminum duals is not only time consuming, you almost have to be a contortionist to do it.)

However, it’s important to know that these valve caps can be over-torqued, which will distort the internal seal in the cap. Inflate-thru valve caps should be installed hand tight. I’ve heard of some people installing these caps extremely tightly with pliers to prevent theft. You’d be better off using Lock-Tite than risk damaging the valve cap.

Ideally, valve stems should be replaced every time a tire is replaced, and inspected every time a tire is balanced or the pressure is checked. Make sure the valve core is free of debris and always make sure a valve cap is used.

When installing a valve always check the rim hole for nicks, burrs or corrosion. Remove the burrs and corrosion to prevent damage to the valve stem grommet or O-ring. If you see nicks, smooth them out being careful to keep the valve hole round since they will cause leaks around the valve stem. Valve stems commonly used in medium truck tires such as the TR570 series valves should be torqued to 30 to 45 inch pounds.

It makes good sense to install quality air retention hardware. If you are careful in selecting and running high-quality tires and retreads, treat your tire valve hardware with the same importance. Don’t jeopardize the health of these tires for a few cents saved on valve stems, cores and caps.