Just a question that's been bothering me. I put a Specialized Hemisphere semi-slick on my rear mountain bike wheel. The max psi printed on the tire was 80. I pumped it up with my floor pump and when the the pressure got to 60psi...BOOM went the tube. Blew the tire half off the rim too. The tire was within size parameters for the wheel, and the tube was the right size for the tire. I checked the pump's pressure gauge with another gauge and it was off by about 5psi, but still I was well under the 80psi max. Also, the same tire/tube/wheel combo installed on the front was fine. All I can figure is I had the tube pinched or the tire mounted incorrectly, but I thought I had installed it pretty carefully. Any thoughts?