Yes, tread is a Scrabble word!

Verb

1. Put down or press the foot, place the foot

2. Tread or stomp heavily or roughly

3. Crush as if by treading on

4. Brace (an archer's bow) by pressing the foot against the center

5. Apply (the tread) to a tire

6. Mate with

Noun

1. A step in walking or running

2. The grooved surface of a pneumatic tire

3. The part (as of a wheel or shoe) that makes contact with the ground

4. Structural member consisting of the horizontal part of a stair or step