Was just about to go out for a ride with my friend tonight when she rang to say she had a flat tyre (and no spare tube, so she stayed at home). I went round later, and out of curiousity tried to work out what had caused the puncture. Looking at the tyre, there is about a two inch tear on the that seam bit, just where the seam usually sits on the rim, with the tube exposed underneath. In fact, it looks like the seam has simply come apart, you can peel it open now... There are no sharp bits on the rims as far as I can see/feel and she hasn't scraped the tyre against anything, also these tyres have only done about 300miles (they are continental ones, so not complete cheap cr@p), what could have caused this? Is it just a one of dodgy tyre fault or is there something more sinister going on?