Re: failures of tire valve stems 2006 Honda Pilot number of failures: 2 1. events leading to failures common filling of tires with high pressure air lead to disintegration of the valve stem. The valve stem separates at the threads for the valve cap, completely exposing the tire filler valve. 2. this event has occurred on two of the four operating tire valves in this 2006 Honda Pilot. There have been no consequences, but the exposure to tire valve failure from being exposed is obvious. 3. correction requires the complete replacement of the tire valve and its underlying tire pressure sending unit. Failure mode: This failure appears to be a result of the use of soft aluminum in the tire valve stem, the cutting of sharp, V-shaped threads on both the exterior to hold the valve cap and the interior to hold the valve and tire pressure sending unit. The sharply cut threads, compared to conically cut threads, results in fracture when the interior threads and exterior threads cross, leading to minimal metal between the interior and exterior. The failure in one case occurred when removing the valve cap, completely exposing the tire valve itself. The failure in the second case occurred when the high pressure air filling valve (brass) adhered to the very sharp exterior threads and simply ripped the valve stem apart. Note that the valve stem is composed of a soft aluminum, rather than hardened brass or steel. I bring this to NHTSA since, in my opinion, there is a real possibility that these valve stem failures can lead to rapid deflation of the subject tire, loss of operator control, and consequent accident and injury if the valve stem separates such that the integrity of the tire valve is damaged. In my estimation, this is as significant a problem as was the historic sudden tire tread separation issue. In fact, this problem can result in the same unexpected loss of tire integrity if the tire valve is damaged subsequent to a failure in the valve threads.

- Fort Collins, CO, USA