Ask the Expert: Why is it when I use valve extensions, my tires lose air after a while?

Question: Why is it when I use valve extensions, my tires lose air after a while?

Answer: 

Traditional valve extensions are either rigid, chrome-plated brass tubes or braided stainless steel and rubber extensions. In either case, the valve core is removed from the valve and the extension is now a pressurized chamber. Over time, the rigid extension can vibrate loose from the valve and cause a leak at the connection. With the braided version, the rubber begins to break down at the crimp point and a leak can occur. Since the core is removed from the valve, the air leaks out of the tire if these are broken. There is a solution though; Air-Flexx from Ken-Tool. These extensions are a lightweight polymer-coated stainless steel jacket over an inner air pipe. A moving inner pin opens the core that remains in the valve. These are flexible but rigid enough to eliminate the need for a stabilizer. Since the core remains in the valve, there is no loss of tire pressure if they are severed or broken. The extensions come in a variety of lengths, 2-15/16” to 39-1/8”, and the longest can be used on those hard to reach spare tires on pickup trucks and vans.  

Information provided by Ken-Tool