Quote:Sometimes, just sometimes, the core in the tyre valve can unseat itself and not seal properly. Pumping it up again would have moved it an maybe re-seated it. It may be a good idea to remove the core and give it a clean. It has happened to me on a car. Either that, someone was messin' with ya!I remember reading years ago that Schrader made a specially strong racing spring for valve cores. It was thought that a high enough centrifugal force could overcome the spring pressure and unseat the valve. Just like you said.  However, honest guv, I never went that fast !
Good point though, I'll take out the core and give it a close inspection, maybe even replace it.Â