Are these tires worn out or was it rather a manufacturing defect? On both of my tires (conti 0101442 or 0100175, can't remember), I got a fissure running almost uninterrupted all the circumference. It's not in the middle, but rather shifted to the left, on both of them.

They are two or three years old. The bicycle is stored on a wheel hook, tires do not touch anything. The shelter is fume-free.

I wonder what is it likely: wear, manufacturing defect, over-pressure?




Edit: Thanks for all the replies. They reminded me that the tires were sold folded several times. I'm not saying that it led to the defect, though. I tended to inflate to the upper pressure limit (and never bothered to compensate for afternoons warmer than mornings etc)
It looks like age/exposure related failure from what I can see. If it is a defect the shop where you purchased them may pro-rate them on new tires. If they do this it would be a good will gesture on their part. I worked in the retail automotive tire world and it is nearly impossible to get a defect related replacement from the manufacturer. They blame under /over inflation, road hazard, sun exposure etc.