I guess it's a bit of everything, but i have a feeling that it won't happen with thicker tubes. still, the kinlin rims are far from a perfect design i think. smae with ultremo tires, that keep on bringing out a thread on the sidewalls. i cut it when i see it and then appears again...

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Happy Trails !!!

Just the other day I read something on Schwalbe's website, that there was a bad bunch of Ultremo R tires in circulation and they described just the same thing as you do.
It also said that if a costumer experienced such issues, the costumer should take a picture of the thread and one of the serial number on the inside of the tire and mail these to ultremo@schwalbe.com and they would send you a brand new tire.
I know that you ride on the ZX and not the R but I think it's worth a try!

thanks mate. i will definitely try that.

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Happy Trails !!!