Review on 🚚 Pacific Dualies 18101 MAX EZ Air 7" Braided Stainless Steel Valve Stem Extensions with Small EZ Wire Clip - Ideal for Ford E350/E450 Dually Trucks, RVs, and Motorhomes featuring 2" Round Vent Holes by Adam Rogers

As the description says, this is exactly what you need specifically for the E350/450 twin 8-grip rear wheels. cannot be installed. One of the pictures in the above description shows the installed extension coming out of the outer rim inspection hole and being held in place by the rim clamp. This doesn't happen. After threading onto the inner valve stem, the extension extends 2-1/2 inches past the hand hole. The fixing nut that threads onto the end of the extension cannot be tightened to the clamp as instructed. This requires the extension to be 2-1/2 to 3 inches shorter. If someone tries to bend the extension back far enough to actually tighten the nut on the clamp, the valve stem will likely be stressed enough to break it. There are many satisfied users, so before buying, I advise you to research how to install them. For me they are back.