strange tire question

I replaced my standard valves with nice brass extended types and somehow, one of them developed a fairly fast leak...like yours. The extenders I installed are the type that are installed in the wheel when the tire is off. A trip to a local tire shop took care of it as they just had to replace the damaged rubber seal on the leaking air stem and all was good. Free too. Seems as though the original installer hadn't been too careful and tore the rubber seal when he tightened it down. It failed over a year later.

Another time, cool evenings would often give me a very low tire in the morning, always found just as I was leaving town. After several delays at tire shops without finding the leak over several months of driving (intermittent air loss is frustrating), finally discovered with an immersion test early one cold morning that the steel rim had somehow developed rust spots...tiny holes all the way through the thick steel. Patched them with Eternabond, and two years later, that tire/wheel was still going strong with no leak. Sold the rig, and it's probably still OK.

Also, a nail can cause a leak like that.

Just three of many possibles. Good luck finding yours!