MinnMan

OK, I get the idea. I tend to think that even the smallest puncture in a tube will result in a more conventional "fast" leak - because I've seen so many normal punctures from tiny wires and objects. These would be punctures where the hole is nearly too small to see, but the tube won't hold any pressure at all because the hole aperture widens as soon as the tube is pressurized. So my intuition (which you all say is wrong) is that slow leaks aren't from tube perforations.

I've looked over the tire in great detail, turning it inside out under a bright light, and I don't see any protruding objects. But it's an old tire. Maybe it's time to replace it and move on.

Thanks for the input.