I often wondered about the engineers who design these things. They must have infants' hands or something. I have wheel inserts on my dually. I take them off to get at the valve stems. There still isn't a whole lot of room to get my hands in there. I originally installed air valve extenders and on a trip last year got a flat on the left rear outside dual. As it turned out, it was the valve stem that leaked air. It was the rubber part that split. The valve stem extenders moved a lot while driving. So I had a tire shop remove all the OEM stems and replaced them with brass ones. Problem solved...but I still have to remove the wheel inserts in order to air up or air down the tires depending on whether or not towing. The original valve stems were high pressure stems but had rubber at the base of the stems. The new ones are rock steady so the extenders do not move around at all.....so be aware of a potential problem.
