Chromed Valve Stems: Do they leak?

[MIK911]

Do chromed valve stems leak air more than the garden variety rubber ones used on new tires? I've heard this in the past, and currently i have two other cars, a Jeep with rubber stems with no leakage, and a BMW with chrome valve stems that leak about 4-5 psi every month or two. Any ideas?
Thanks
Mike

[GeorgeK]

Hi Mike,
There are two things here:
First the "deco" valves which are rubber, and on which the chromed cap extends as a sleeve on the rubber stem, to make them look like the race stems. These should not leak more than std stems.
Then there are the racing stems, which are made of metal (brass or aluminum, usually), and are screwed on the rim. These can leak over time, but it is not an issue on race cars, which are checked often and on which the tires are changed often. These racing valves look cool, but yes they leak. Another problem is that you tighten a metallic screw on a nice alloy rim, possibly damaging the surface. I've seen BAD corrosion on Fuchs, caused by some galvanic corrosion between the (damaged) anodised aluminum and the metallic stem. I wouldn't use them on a street car.
There's a nice option, it is motorcycle stems. They are very short, like 1/2 inch and are rubber. Looks great, while remaining harmless for your rims.
GeorgeK