Mystery #2Tier 2friction

Why do tyres have grooves carved into them?

Racing cars on a dry track use completely smooth tyres, yet your family car's tyres are covered in grooves. If smooth tyres grip best, why doesn't every car have them?

Close-up of a car tyre showing the grooves carved into its tread. — Photo: Jbobby · CC BY-SA 3.0 · via Wikimedia Commons

Your guess

What's your hunch about why normal car tyres are covered in grooves and channels?

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