Originally Posted by DBrim

My relatively-new-to-cycling flat tire odyssey did indeed continue today. I commuted in just fine, but noticed that my rear tire was flat yet again early this afternoon. Luckily being indoors and not in a hurry as opposed to on the side of the road led to a more thorough investigation, and I was able to find an offending bit of glass wedged deep into the tread. I did not feel it on the inside, but there was indeed a small tear on the inside wall of the tire, so it must have jostled in when I hit some bumps. That would also explain how the tire was able to hold pressure overnight.

My second tier spare is labeled as "thorn resistant." I bought that online without noticing. Man is it heavy. We'll see how it rides, it might be worth swapping out again after I patch the last two days worth of tubes. Still, I might stick with the heavier tubes when I switch to the studded tires in a few weeks, because getting a flat in the winter sounds... bad.

Learning!