Review on Xtra Seal Black Plastic Valve Cap by Steve Collins

It's always annoying to lose a valve cap or it breaks and you can't replace it until you're in the shop. It then costs about 50 cents for a pack of 4. It's not so much about the cost as it is about keeping the valve open to the elements until you can properly shut it off. What can go wrong? If dirt, usually coarse like rain puddles, surrounds the valve stem and if it is not completely removed and then filled into this tire, some of the dirt can coat the sides of the stem seal and cause slow leaks. The only way to safely fix this is to overhaul the valve. You can avoid this problem by always capping the stem and keeping a supply of valve caps on the machine. If you get dirt on the stem, rinse it with water before inflating the tire. Thoroughly dry the tire before inflating to avoid water entering the tire, especially if you have a TPMS sensor to prevent premature corrosion. These caps work great and cost about 6 cents each. I just leave a handful in a ziplock bag in each of my machines and use them as needed. Now I don't have to worry about lost caps anymore. If you have a TPMS system consider buying TPMS style caps, they cost the same but have an o-ring on the cap to make it more waterproof and prevent contaminants from getting into the penetrate the valve. If you have a bike they work too. Finally, in TPMS systems, the valve stem has metal parts and a battery. Metal valve caps may not be compatible with the stem metal and you risk corrosion or fusion of two dissimilar metals due to galvanic attack. And the safest thing to do on vehicles with TPMS systems is to use plastic valve covers instead of metal covers.