Get some DH tubes dude.....check your rim to make sure the rim tape is all there. I run DH tubes for any kinda riding I do.....I just dont feel like getting a flat. Also, dont run the tires below minimum, really depends on how much you weigh though. The tubes im running now are 2mm thick, and im running them at 17-23psi for downhill, and 40psi for normal riding. I run Intense909's for DH, and gazzi's for everything else. The 909's have a seriously thick sidewall. The Nokians flatted when I ran them at 25psi in a DH race....so theres also a patch in it. DH tubes are good if you dont mind the weight.