Got home in the early hours of this morning (4am to be precise) and could hear a faint hissing when I put the car in the garage. Couldn't see anything with a torch and first thoughts were that it might be water splashed onto the exhaust.
Get car out of garage this morning and rear nearside tyre is half flat. Inflated it and drove down to ATS.
This was we found when the wheel was taken off the car: a damn great cut in the tyre
That's not the whole story though. Upon further inspection of the tyre, it showed similar cuts and small cracks appearing all the way around the inner edge of the tyre. Tyre could have given out at any time.
To say I was lucky is an understatement. I'd just completed a 200 mile round trip to Birmingham and back on this tyre on the M40 and A34 at, lets just say, a high speed.
I regularly inspect my tyres for wear, but this couldn't be seen unless taking the wheel off the car.
I got ATS to check the offside rear, and that tyre has a few small cracks appearing in it as well. No where near as bad as the nearside one though. eg, like this one http://img835.imageshack.us/img835/674/imagexlf.jpg (this is a pic of the above faulty tyre, not the one from the offside. Used to show the sort of cracks that have started to appear in it)
Guy at ATS says he's seen it before on BMW's and other Vauxhalls. Main cause being the rear wheels have a negative camber and the inner edge wears more than the outer edge.
Fortunately I had an old tyre kicking about the garage to save having to put the pram wheel space saver on. New tyres on order from Camskill - cheaper than ATS can do them for.