After an investigation by the National Highway Traffic Safety Administration’s (NHTSA) Office of Defects, Dill Air Controls Products is recalling nearly 2 million tire stem valves sold nationwide between November of 2006 and July of 2007.

The impacted model numbers are TR413, TR414 and TR418.

Detailed instructions for tire professionals are available at www.dillaircontrols.com.

According to NHTSA, “These valves may lack the required additive to protect the rubber from deterioration from ozone exposure. As a result, affected valve stems, when subject to high levels of ozone, may weather and crack earlier than normal for this product.”

Over time, such a crack could progress to the point that it leaks, resulting in a loss of tire pressure leading to a flat tire or sudden vehicle control problems that could cause a crash, the agency notes.

The snap-in rubber valve stems being recalled were manufactured by Topseal (Shanghai) Auto-Parts Co., Ltd., in Shanghai, China, and imported and distributed by Dill under the Dill ACP brand name.

Dill advises anyone who bought new tires between November 2006 and July 2007 containing a Dill valve cap to have the stems inspected for cracks. Dill stems from this time period exhibiting cracks in the rubber will be replaced for free.

The company says consumers can check their own valves by flexing the valve outwards toward the tire and inspecting the area where the valve meets the tire rim, or they can return to where the tire was bought for a professional inspection.

If anyone is unable to return to the point of purchase, they can have their valves inspected at a participating Sears Automotive Center, Tire Kingdom, Big O Tires, Les Schwab Tire Center, NTB or Merchant’s Tire.

Dill says that at this point in a recalled valve’s lifespan, any cracking will already be visible.

The problem relates to two specific lots manufactured in July of 2006. Based on field returns and testing data, Dill believes that the number of valves from the two suspect lots subject to increased cracking risk is 200,000 or fewer. However, the valve stems are not traceable by lot number once the stem is installed; thus the recall includes more valves than are likely to contain the defect, the company says. Consumers who are unsure if their current valve stems were purchased during the recall period should have the valves inspected.

To prevent a recurrence of the problem Dill and Topseal have been using an enhanced rubber compound and implemented an automated inspection system to ensure all the additives are mixed properly along with performing more valve testing in the U.S. and re-establishing domestic valve production.

For more information, visit www.tirevalverecall.net, www-odi.nhtsa.dot.gov/recalls and www.dillaircontrols.com. The NHTSA Auto Safety Hotline phone number is (888) 327-4236.