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The Forgotten Valve Stem


The Forgotten Valve Stem

If industry pundits are right, you can expect to see EPDM (ethylene propylene)

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snap-in valves give way to aluminum clamp-in valves in the near future. But they may make a comeback.

Confusing isn’t it?

Credit the expected change to the TREAD Act and its TPMS imperative to carmakers. By 2007, all new light duty passenger vehicles must have a TPMS, with phase-in starting with 2004 vehicles.

Already a number of TPMS manufacturers are using the back plate of the more expensive aluminum clamp-in valves to house their transmitters. The aluminum clamp-in valve is preferred because the 1 1/2- to 2 1/2-inch molded plastic TPMS units fit nicely on the valve’s back plate. From this mooring spot, signals are then directed to a receiver that relays the information to in-dash displays.


It’s a tidy idea and, according to the manufacturers, one that works very well. Even so, there is a question about product life given the hostile environment in which these TPMS units must function.

There are concerns, but tests show that these valve-attached systems will work. Of greater concern is the cost that automakers will have to swallow.

Experts say carmakers used to paying 15 cents per tire valve will choke on the cost of an aluminum valve with a TPMS transmitter attached – estimated to be at least $6.50 per wheel.

Will carmakers buy this proposition? Not any longer than they have to, which is where the future of tire valves muddies a bit.

Getting in Tune

Tiremakers are as involved in TPMS as anyone. While playing their cards very close to the vest, all of them are talking with carmakers right now and are telling them what they want to hear.


Some of tiremakers are said to be less interested in TPMS as we know it and are in favor of embedding a dime-sized sensor in the body of the tire itself. In turn, that unit will transmit inflation pressure information to a display inside the vehicle.

Others are looking at transmitters attached to the wheel or to the tire valve. Regardless of the method, the issue is their ability to deliver TPMS concepts in a timely fashion. The end result may be an overlap between yet-to-come technology and the already-approved systems carmakers are rolling out.

During this transition period – possibly two years ®“ tire dealers may see an increasing use of aluminum clamp-in valves.

Still More Problems

Still another issue has to do with aftermarket wheels. Some say as many as 20% of all aftermarket wheels will not accept any type of tire valve/transmitter combination. Others say the number is much higher.


Hole size, position and angle of the vale stem hole simply won’t permit it, says one source. In fact, at least one maker of TPMS units recommends its system for use only on OE wheels.

There is also the matter of false readings. An unreliable signal sent to the dashboard won’t please anyone. While consumers will expect to trust the system, they won’t put up with very many false warnings.

Current reliable technologies are expensive, but will come down over time. Future TPMS technology may eventually tell motorists how much tread life remains, alignment and balance conditions, tire rotation updates, tire temperatures and, of course, inflation pressures.


All of this information could be presented in a dashboard display by wheel position, and maintained in an on-board database. When consumers get a reliable, time-tested taste of the future, they’re going to like it.

Snap or Clamp?

Already we’re in another type of transition period, one that will last five years. If tiremakers roll out an embedded TPMS sensor, we will see carmakers revert back to less-expensive EPDM snap-in valves. Ford is already leading the charge and may well turn off the faucet for clamp-in valves sometime soon.

Remember, this is still a story on the tire valves. Rubber or metal, tire valves are at the center of this conversation. Or would controversy be a better word?


The latter becomes operative if carmakers juggle a mix of rubber and aluminum valves for too long. Worse, what if aftermarket wheel makers do not, or cannot, adjust their valve holes to meet transmitter specifications?

If the transition period unfolds in this manner, dealers will have to stock both EPDM and aluminum clamp-in valves in various sizes to fit the OE and aftermarket wheels they see.

Customers, being what they are, will want you to install a clamp-in aluminum valve – with TPMS transmitter attached ®“ on their expensive wheels, no matter what the hole configuration.

On the other hand, says Pete Fountain, a HalTec engineer who sits on the Tire and Rim Association tire valve committee, "Finding a regular snap-in valve for aftermarket wheels can be a problem right now."


He speculates that if one aftermarket wheel maker moves to standardize hole configurations, others will follow.

Speaking of snap-in or rubber valves, there has been a growing worry about certain all-natural rubber valves entering the U.S. According to reports, such valves are unable to withstand the constant assault of ozone, weathering and normal service abuse.

The good news is that some offshore valve makers are now employing compounds in their valve stems that successfully combat ozone and weathering.

Experts do say dealers should not install tire valves that do not meet OE and SAE standards. These valves must also pass ozone testing and be made of EPDM rubber. The manufacturer’s name should also be on the valve.


Other Alternatives

Other technology is finding its way into the valve industry. International Marketing Inc. (IMI) says its Air X valve core has a protective filtration system that won’t allow the valve core seal to become contaminated with dirt, rubber particles or debris.

According to IMI, the filtered valve core seats firmly into the base of the valve stem housing, and "keeps contaminants inside the tire from reaching the valve core seal."

In July, IMI introduces a new valve stem with the Air X filtered core inside.

In the meantime, as the entire TPMS saga unfolds, don’t be surprised to see EPDM rubber snap-in valves taking a back seat to aluminum clamp-in valves for about 24 months before making a comeback.


Finally, don’t rule out an effort by automakers to pull car buyers into new car dealerships for TPMS unit replacement and repair, including the installation of metal clamp-in valves with transmitters attached, if that turns out to be one of the TPMS solutions.

In some cases, these valve/transmitter units may not be available initially in the aftermarket. But if history is any lesson, OEMs will once again look to the aftermarket to bail them out. They always have, and they always will.

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