Again with the tire tread, right?
There are so many things you can do with these otherwise discarded necessities. We have an extreme hill in our backyard and years ago we cut them in half and buried the ends into the base of the hill. Over time it has filled in nicely with ivy and monkey grass (we planted). I've never been a big fan of tire planters in the front yard, but I do like the way this subtly blends into nature and most importantly: It works great!