[pitmaster]

prickle, thorn, defect valve, pinchted tube, etc etc

either way tubes gotta come out (except valve), so pull it out, pump it up and put it in bucket of water and see where its leaking,

either patch the tube if its a hole, or buy new tube,

if its a hole make sure you check the tire for thorns etc, and carefully check inside the tire for sharp bits, you dont wanna just replace the tube, than when you pump it up again the same thorn pops your new tube haha,

goodluck