What does a vehicle's tire tread depth affect?

Answer: C — Both fuel efficiency and brake performance

Tire tread depth plays a critical role in both fuel efficiency and brake performance, making the choice of both aspects the most accurate answer to the question. For fuel efficiency, tire tread depth can significantly impact how well a tire grips the road. Tires with adequate tread depth maintain better contact with the surface, reducing rolling resistance. When tires are worn down, they can create more drag, which requires the engine to work harder, subsequently reducing fuel efficiency. Therefore, ensuring that tires have sufficient tread depth helps optimize fuel consumption. In terms of brake performance, adequate tread depth is essential for ensuring that tires can effectively displace water on wet surfaces, thus reducing the risk of hydroplaning. Deep treads provide better traction in both dry and wet conditions, allowing the vehicle to stop more quickly and safely. Insufficient tread depth can lead to longer stopping distances and potentially hazardous situations. Thus, the correct choice encompasses the vital roles that tire tread depth plays in maintaining both fuel efficiency and effective braking performance.