I had the same problem. Bad extension, flat tire. I went to Les Schwab Tire Service Center and they sold me a 6" chrome extension that will not let air escape when the extension goes bad but allows you to air up the tire. I have not been able to find this same kind on Amazon, E-bay or NAPA. I will have to go back to Schwab and by more. They are a little expensive but will not cause a flat. When I find out the brand I will come back and let you know.
1997 Triple E Empress, Freightliner Chassis, CAT 3126 w/ 275 horse's.
MD 3600 Tranny, 2011 Ford Escape Hybrid w/Blue Ox tow bar and Roadmaster Base Plate.
Amsoil Synthetic Oil only for my baby.