I think this is normal for the Russian tyres. They have multiple layers of tread reinforcing plies on top of the carcass plies. Even though the cords are showing there is still visible tread (and tread grooves) on all tyres. I remember a UK One-Eleven operator using tyres like this years ago. I think it was EAC when they first got the -510's off BA. Even a brand new tire had plies showing with a full tread groove.
As for the "crack". It's a poor quality image but possibly is stop drilled which means it's been inspected and probably documented somewhere.
Nice livery that Balkan Holidays, been in STN many times.