Possible Clues:

• Tramp with the characters in theatre adaptation
• "___ lightly"
• Walk with energy along Dart upstream
• Pattern of tire ridges
• From surface of tyre, study this?
• Part of a tyre
• Top surface of a stair step
• Poorly rated walk
• Walk over: time to pick up a book
• Tire part that might be measured with a 'penny test'