Our Jayco Class C came with valve stem extenders. They worked okay. We had a problem once when I went to air up one of the inner dual tire and it wouldn't take air. I had to pull the simulator, remove the extender and put it back on. I had to do this twice before it finally started to work properly.
When we replaced the tires, we had the tire shop install
Tire-Man Dually Valve Stem kit. These made checking and airing up the tires so much easier (even easier than with the valve stem extenders).
-Michael