Originally Posted by KevinF
Subject heading pretty much says it all. My tire has a presta valve; if I unscrew the top and push it down, nothing happens. My pump won't put any / much air in. I just want to replace the tube, but there's no way I can fit tire levers in there until the tube is deflated. What other options are there for deflating tires? I'd rather not stick a knife through the tire and pop it as the tire itself only has a few hundred miles on it. Can I cut the valve stem? Would that deflate the tire?
How far do you unscrew it? All the way?
Also what happens with "nothing happens" when you push? Does the valve-stem go down 4-5mm so that the screw-head is flush with the tip? Or it doesn't get pushed in at all? If it doesn't push in at all, I say push harder.