I had an expensive set of valve extenders on my motor home. One leaked, I almost lost a new $400 tire!
I recently purchased a Toyota motor home, on the drive home I heard a funny noise and wondered what it was and then BAM an inner dual self destructed. It was an old tire, when I was checking things the valve extension was broke.
Did the blowout break the valve extension, or did the broken valve extension cause the blow out? I'll never know.
Proper valve stems can be purchased along with gauges and inflators that will work with them. Only way I go.
I also use the 78% nitrogen fill. Jim
Jim