one tire or tyre has more depth of tread and the other tire or tyre has less depth of thread = the amount of visible tread before the tire is legally bald and smooth. Or showing the inner cloth fabric below the rubber.

Ok it’s when something called your car alignment is off. It’s referring to one tire or more than one. Usually one side. A single tire has uneven wear so one half of the tire is fine or better but on the other half the rubber is wearing down more due to the total central alignment of the tires is not correct. If this happens you have take your car to have the wheels aligned at a mechanic shop. They have a special machine that aligns your tires so that uneven wear doesn’t happen with the new tire. After every time you change your tires you should align them but they can get off the alignment for many reasons. A small accident, maybe you hit a pothole 🕳 really hard like boom 💥 and now the alignment is off. It can just happen for no reason. Check out my teacher profile www.italki.com/teacherhelpme Thanks