I don't know what it is but I keep dealing with flats on the trainer. From the holes that I find it actually just seems like the heat of the roller is killing the rubber. The rubber continually seems to be falling apart and multiple holes forming until one pops through. Old rubber + heat?Plan to ride the trainer early this morning. Install an old tire using the good tire's tube the day before. Get fully geared up, go to the detached garage, and find the rear tire deflated at 5am.