Quote:
Originally Posted by evolutionmovement
The rubber stems are just that and you can tell by looking at them. Metal ones look pretty much the same but with a metal sleeve over them. Chances are very good you have the rubber ones as the metal's are extra charge and usually people only use them on alloys. Pretty much any tire place should be able to put in the longer stems for you next time you get tires (or you could have them just swap the stems, but they might charge you for mounting and remounting the tires when all they really have to do is deflate them, compress the sidewall near the stem, swap the stems out, reinflate. Either way, they've got to charge you something). They might tell you not to use the rubber stems as the edge of the hubcaps might cut into them, but I don't know. In my experience, the metal stems are much better at holding air and are reusable, but I don't know if they come in long versions.
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The valve stems with a metal sleeve over them are
not metal stems. You can find metal stems easily on most split rims, and large trucks in general, and less often on cars and light trucks. They are actually metal, they bolt into the rim, and the only rubber pieces on them are the seals under the nut and above the base of the stem (the part that goes inside the wheel/tire assembly) and the rubber on the valve core itself, which seals the valve stem's air passage. You may also find rubber under the caps, in some cases.
Most tire places will refer you to buying "high pressure" stems, often used with tires which denote a sidewall max inflation higher than 60PSI, or have a load range of "E" or higher. They will often tell you that these are "metal stems" that you are looking for, though they still don't bolt in. These are in fact metal, but surrounded with a rubber gasket, which pulls through and seats the same way a traditional rubber stem seats. They can still leak if offset to an extreme angle, and they will still rot due to environmental stresses.
All-metal, Bolt-in style valve stems are more economical, in that they never need to be replaced, and the seals can be made from very thin and small pieces of recycled or repurposed rubber, or they can even be sealed with normal form-a-gasket type sealants, like Silicone caulk and RTV silicones.