Related Clues:

• It gives a tire its grip
• It's worn while driving
• Pile-of-dishes place
• Dirty dishes collector
• Firestone surface
• Auto-tire surface
• Dig as for well
• Walk or step
• Walk or step like pattern on tyre
• Drop beneath the surface
• Fall to the bottom
• Grooves on tyre
• Plumbing fixture
• The sort of measure that might get round a horse
• It's wrong to start to go down the drain from this