Originally Posted by Juha
I've had a couple of spells like that, and on both occasions it turned out to be a piece of glass buried deep into outer tyre. When inflated it would press against the tube, causing a slow leak. When I took off the outer tyre I could not find the hole on the inside surface. I could spot the hole on the outside, and after looking very carefully in there, locate a small shrapnel of glass. Last time I had to use a bright LED light to find it, and some small pliers to get it out.
I suggest you take one last look at that tyre, and if you still cannot find the reason, just replace it to cut your losses.
--J
I've had the same situation, which is why I did a lot of twisting an flexing. I also probed in the hole left by the first flat, looking for glass. Nothing.
I also don't know why they would be so close together yet be too far apart to seem to be from one specific cause - unless there actually can be some variation even when you line the tire up the same way each time. Let's see, I can't say exactly where all the flats were, other than the three in this specific tube. They cover an inch or a bit more. So the center point would be about a half inch from the two extremes. Can a tube vary that much? I wouldn't think it would vary at all, but maybe so.