Old Ryder--Hope I'm not high jacking your thread but I do agree with others on replacing the OEM valve stems with metal ones. I have used steel ones like the ones shown in previous posts but also found some that had the locking nut on the outside. I believe that's a good thing (pic below). I'm not sure I can find those again but would have to search. Since using steel stems, I have further upgraded to aluminum stems which I like even better. They are much lighter and still very strong. The ones I've been using come from KurveyGirl.com. Here is the pic of both steel and aluminum stems that I've used:

Attachment 20648

One note...if using the aluminum stems like shown, you will need to grind off a bit of the aluminum casting that the plastic "keeper" attaches to. That is easily done.