Steel braided lines
I have a set of steel braided Air Valve extenders for the inside and outside wheel, that are attached to the center hub cap. You can find those at your local RV Accessory department. The only gotcha is to make sure your wheel's original valve stem is a steel one. If you have the rubber valve stems, they will get ripped right off, in a very short time. I'm speaking from experience. I had to replace the valve stem on my inside wheel with a steel one. The outside wheel (Alcoa) already comes with a metal valve stem. Hope this helps.