Answer:
I start new then become old. Start clean but become dirty. I usually start big then become little. What am I?
My rings are not worth much, but they do tell my age. What am I?
I run smoother than any rhyme, I love to fall but cannot climb. What am I?
The more holes you cover the lower I go.
What goes up but never comes down?
Strip the skin under my skin, and my flesh you'll reveal. It tastes sweet and tart, now throw out the peel. What is it?