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Ive been riding and racing for 25 years now (well longer than that, but I don't think the years riding my Raleigh Striker count) and have never ripped a side wall, until this year I have split four. All Cyclocross tyres.
All were run at the correct PSI, two were only a few rides old.
What am I doing wrong?
Middle age spread? 
Thanks Nobeerinthefridge. Ive dropped 10kg and come in at about 92kg, so I'd hoped that wasn't the issue... 🙁
Riding somewhere with sharp rocks?
Have you got a sharp edge on your rim?
A while ago I had a bit of a sabbatical with Continentals as I tore so many of them across different bikes directly adjacent to the bead. I've only ripped one other sidewall ever, which I think was just an unfortunately placed pointy rock.
That does seem a lot to be a coincidence. Have you checked the rim?