I am having difficulty in getting air in the back tires. I bought a rubber extension for them, however just got back from a camping trip and the one back tire had lost all but a few lbs. of pressure. I also bought a 90 degree angle to put on the extension so I could get air in the tire. The extension got loose that why I lost the air. Anyway does anyone know of a better product that I can put on the rear wheels. This is my first Dually, so am really new to this sort of thing. Thanks.