Quality name-brand snap-in valve
stems from reputable suppliers for passenger car/light truck applications
typically cost from 16 to 25 cents per piece in bulk quantity vs. maybe 11 to
12 cents each for "no-name" imported stems in bulk (NOTE: these are wholesale prices).
For grommet-style truck valve stems, a quality brand may sell for $1 each compared to 60 cents or less
for a no-name brand.

A few cents difference in price may not seem like much, especially when most parts stores and tire dealers charge $2.50 or more to their customers for an installed valve stem. But the price does reflect the underlying quality.

Frank Banzanhof of Schrader Bridgeport International Inc., Muskegee, Okla., a manufacturer of OE valve stems, says many import stems are made of natural rubber rather than EPDM, a tougher synthetic rubber used in most quality valve stems. EPDM has a much broader temperature range than natural rubber, and remains flexible in the coldest weather. It also resists ozone and chemical attack that deteriorates natural rubber.

"The materials they are using will not pass the SAE 1205-1206 ozone requirements, which is a standard created by the Society of Automotive Engineers. No vehicle manufacturer will accept a valve stem that doesn't meet this standard."

Banzanhof cautions that using valve stems made from low quality materials is asking for trouble. After only two years of service, natural rubber valve stems dry out, he says, becoming hard and brittle, allowing for cracks and leaks.

Unfortunately, there are no government standards that apply to valve stems. The Tire & Rim Association publishes a yearbook that lists standards for valve stem dimensional tolerances, but the group does not get involved with performance standards.

Finding Quality Stems
So how can you tell if you are buying a quality valve stem? Banzanhof says to ask the valve stem supplier if their product meets the SAE 1205-1206 standard. You should also ask if company that manufacturers the valve stem is QS9000 or ISO9000 certified - both of which require meeting stringent quality control standards, procedures and recordkeeping.

People should watch out for no-name valve stems, according to Norm Prinzo and Dave Magoulick of the Akron-based Myers Tire Supply "If you don't see a manufacturer's logo or country of origin on the product, I'd be very suspect of it. If there's no identification on the valve, who's going to stand behind it if there's a problem?" asks Prinzo.

"A no-name valve stem may look and fit okay today, but how long will it last? The life of the rubber is determined by time and temperature. Many tires last a long time - up to six, eight or even 10 years. Truck applications are even more demanding because of the miles driven, heavy loads and extreme operating environment," said Magoulick.

Valve Stem Replacement
Most valve stem suppliers say tire dealers should always replace the valve stem when replacing a tire. Valve stems should also be inspected anytime a tire is balanced, repaired or dismounted. A valve stem that is cracked, damaged or leaking must be replaced.

Valve Stem Replacement
Before removing a valve stem, determine if the vehicle is equipped with valve-stem mounted Tire Pressure Monitoring Sensors (TPMS). Attempting to pull out a valve stem with an internal TMPS sensor will destroy the sensor (which can be very expensive to replace). On TPMS applications, the tire must be deflated and separated from the rim or dismounted to remove the valve stem.

Before installing a new valve stem, inspect the hole in the rim for nicks, burrs, corrosion or other roughness that could damage the new valve or prevent a leak-free seal. Most valve stems are coated at the factory to maintain their appearance and to ease installation. If a lubricant is used, do not use a petroleum-based product (rubber absorbs oil). Carefully pull the valve into the hole and make sure it is properly seated.

On some light truck applications, special "high pressure" valve stems may be required (refer to the pressure rating of the tires). Most passenger car and light truck valve stems are only rated to a maximum of 65 psi, so if the vehicle has high load tires it will require high-pressure rated valve stems.

On TPMS applications, the valve stem may have a seal and an external nut at the base to hold it in place. This nut must be tightened to specifications with an inch-lb. wrench. Overtightening can damage the valve stem and sensor.

Never assume the old valve stem is the correct one for the application because it may have been replaced previously. Use a replacement valve stem that correctly matches the type of wheel and vehicle application. Many alloy wheels require a clamp-in style valve stem with a threaded metal nut.

On heavy-duty trucks, make sure the valve grommet is the correct size for the hole in the wheel, and that the valve stem is properly positioned for balance and to allow easy air pressure checks.

Finally, make sure the valve core is fully seated and does not leak air once the tire has been mounted and inflated. And always install the cap to keep out dirt and moisture.

WARNING: DEFECTIVE MADE-IN-CHINA TIRE VALVE STEMS RECALLED

Motorists who have had tires replaced or serviced in 2007 are warned to inspect their valve stems for cracks or leakage.
Examine the valve stem and flex it in a circular motion with your finger. If you see any visible cracks or hear air hissing (leaking) from the base of the valve stem, the valve stem is defective an must be replaced. Failure to replace the valve stem may cause the tire to lose air or suddenly go flat. Sudden loss of air pressure at highway speeds can be very dangerous, and may cause the driver to lose control and have an accident or rollover!).