I’ve always had threaded valve stems, using a nut to hold it in place and keep out dirt dust etc. The valve stems on the new PTU inner tubes I just got do not have threads. Noob question: is an O-ring the best way to keep dust dirt etc from entering the valve stem hole in the wheel? I had one and put it on - see pics - doesn’t completely seal around the hole because of the curvature in the wheel.