Small cracks in the tire

Hello you! I have just by chance noticed small cracks in the left front tire. I have no idea where these could come from, I also stuck on my curb. Drive the car only for 4 weeks, got it from my friend’s parents to drive until I buy with my own. White drive enough, how old the tires are and whether the damage was already before, really only a coincidence, that I saw it. Tell her that I should change the tires or p I drive my car every day about 20-30km in the city. Under the cracks is still rubber. Thank you! Lg Sina