Last two days I've had two inner tubes on my front wheel burst. Not a puncture putting the tyre on but an ear-ringing shotgun blast of a burst with the wheel just sitting up against the dining room wall. Both have burst right next to the valve and not when they've just been pumped up either, some time after.
I've checked the rim and there's nothing, the tyres are new but I checked them anyway and they're fine too.
Any ideas?

