What's the cause of this kind of tyre damage? What's causing this type of damage to the tyre?
It's a 25 x 622 tyre on a 13 x 622 rim.
Tyre is a Schwalbe Active Line K-Guard.
The tyre itself doesn't seem worn.
Another possible cause is misadjusted rim brakes where the brake pad makes contact with the tire's sidewall.