What are these cracks in the side of my bicycle tyre called? Does this mean that my tyre is gone?
I'd say, it's time to replace the tire. It doesn't really matter what caused it - could have been low quality, age, or extended use. The cracks mean the layers the tire is made of are separating and in the long run you will see more punctures because the material is softening. A brand-name tire costs 15 to 25 EUR/USD/GBP which I consider low enough to not take the risk of punctures.