On 7/17/14, 2:57 PM, Doug Miller wrote:
KenK wrote in :


Why? I doubt if they would do much, if any, good if the valve was leaking.
They get in the way when checking air pressure - if they weren't there I'd
likely check more often. All I can think of is to keep dirt out of valves?

That's it exactly: to keep foreign matter out of the valves.

I like the aftermarket ones that can unscrew the core. If they were
cast iron, I could find them with a magnet. If a wheel had 6 valves, I
could balance it by screwing on cast iron valve caps of different weights.