OK ..... I broke down and called my favorite tire dealer. He said that any tire with more than 50 lbs is considered a "high pressure tire".
Because our tires hold 75 & 80 lbs, those little valve extenders are high pressure safety features to help keep the air valve from exploding or losing air. I guess that makes sense, so I will keep them on. I had seriously considered taking them off.
Thanks for the post .....