Actually, I was testing the Topeak Joe Blow Sport II pump to see if it could get to its rated 160 psi maximum pressure. That's an old worn out Continental Sonderklasse track racing tubular tire that is rated for 170 psi, and had routinely in the past been inflated and raced at 160 psi. It has been sitting in the heat and humidity of my garage for several years, and I suspect that the cotton casing has rotted. The blowout didn't occur immediately, but many hours later, and startled me when it happened, as it sounded like an explosion. I now keep all my high end tubular tires indoors to protect them from the elements.