Issue with Boardman tubes?

KevChallis

Just swapped from 23c to 25c tyres, I didn't realise that my existing tubes only went to 23c, so nipped down to Halfords (only shop open) and bought a pair of boardman tubes, the front was okay, had some issues with my pump (so I thought) and had to hold it, pushed onto the valve, but it went up, the rear will not however, I have taken the tube off and checked for leakes, and there are none, I have checked the pump on other bikes and that fine, but above 30psi, the valve starts leaking, is it me doing something wrong as never had this before? Or is it just a cr@p valve?

gethinceri

Get some pliers and nip the valve up, it may be leaking.