There’s another safety warning out of the Chinese assembly lines, and this time it involves your car.

There are at this time approximately 36 million Chinese-made tire-valve stems on cars in the United States. The National Highway Traffic Safety Association (NHTSA) is investigating claims that the rubber, foreign air-valves sold between September 2006 and June 2007 crack prematurely, causing tire failure. Complaints of tire failure include reports of fatal car accidents and rollovers.

According to auto-safety consultant Sean Kane, cracks in the rubber near the rim hole of the tire-valve could appear in as little as six months. The defect is most likely caused by the improper mixing of the rubber compound used to make the valve.

The NHTSA has yet to complete their investigation and issue a national alert. Until then, you can protect yourself and your family by continuing to regularly check your tire pressure. If you routinely come up with low pressure, take your vehicle to a trusted mechanic and request an inspection.

Revelations that old, unused tires could be hazardous — and that manufactures chose not to tell Americans about this tire defect — have many scrambling to find out if they have defective tires.

Further, with the amount of letters and numbers on a the sidewall of a tire, it’s no surprise the average consumer has trouble understanding all of this alphabet soup – if the consumer even knows there IS information on the tire.

While some people may know how to tell the tire’s width and size, the manufacturer, and the maximum inflation pressure, it is less common to know how to read the tire’s DOT serial numbering system. This DOT number was never really meant to be read by the consumer, but it includes valuable information about the tire including when the tire was manufactured – something that could determine if your tire is “expired.”

To locate your DOT number, find the 3 or 4 numbers at the end of the serial number. If a tire has three numbers, it means that the tire was made prior to January 2000, and four numbers indicates that the tire was manufactured after January 1, 2000.

The first two numbers indicate the date of manufacture, and the last number indicates the year. For example, 175 would indicate the tire was made in the 17th week of 1995. If the tire says 3206, it shows the tire was made in the 32nd week of 2006.

Some experts believe that tires do have a shelf life and that it is critical to the safety of the consumer. Tires can sit on shelves in stores for years before they are sold. While there is no official expiration date on tires, research and tests show that tires begin to dry up and degrade after about six years of age – even if they’re never been driven a mile.

These “new” tires may look new on the outside, but begin to dry out and lose elasticity. This can cause tread separation, even if the tires have plenty of tread depth. If a tire de-threads at highway speeds, the result could be a deadly vehicle accident. Motorists should check their tires’ manufacturing date and replace the tires after six years of age – regardless of the mileage.

Motorists in Europe and Asia get the warnings, but here in the States, we don’t.

Tires six years old or older are hazardous – even if they have never been used on a vehicle. More than vehicle accident 100 deaths in the United States have been caused by old tires that have dried out and lost their treads, even though the tires appeared to be safe.

While members of the British Rubber Manufacturers Association (which includes Goodyear, Firestone, and Michelin brands) have warned that “unused tires” should not be put into use if they are over six years old, the U.S. Tire Industry Association (which represents several of those same companies) has said it has no plans to issue such a warning. The U.S. Association has gone as far as to say that there is no scientific information that points to when a tire should not be used based on age.

The safety experts in the field feel otherwise; extensive research shows that tires begin to deteriorate in “critical” ways even if they are unused or unsold in inventories. These hazardous tires can remain in a store’s inventory for as many as eight or 10 years.

Experts say that the code on a tire’s sidewall can reveal when a tire was manufactured. The code is at the end of a set of letters and numbers on a tire, and until recently, was on the inward facing side of the tire.

For example, the number 379 shows that the tire was manufactured in the 37th week of 1999 and is almost 10 years old – and has the potential to be dangerous, even if the tread still appears to be in good condition.