LPT: Leaking tire? Check the valve stem. Replacing a valve stem core costs about $3 and takes 5 minutes

This weekend I discovered that my tire with a slow leak was actually leaking from the valve stem. Googling ensued and I found out that replacing the valve stem core is a breeze. If you're not sure if the leak is from the valve stem, spray on some soapy water (just like checking for gas leaks) and see if it bubbles. Mine was actually loud enough for me to hear so I didn't need this step. You'll want to pick up a 4-way valve tool ($1.39) and a package of valve cores ($1.39 for a pack of 4). Unscrew the faulty core using the tool, use the threaded bit to clean the threads, then screw in the new one. Voila! Add air and you should be good to go. Always protect yourself - your tire is under pressure and unscrewing the valve core could send it flying. If you just filled your tire, I recommend letting air out so the pressure isn't so high. If you don't have a compressor at home, you'll want to make this repair in a location where you have access to air.