Final answer:
Advisory speed plates provide maximum recommended speed for curves or turns, indicating the safe speed without relying on tire-road friction.
Step-by-step explanation:
Advisory speed plates are small signs placed below curve or turn signs to provide the maximum recommended speed for that particular curve or turn. These plates are used to inform drivers about the safe speed to navigate through the curve or turn without relying on friction between the tires and the road.
Ideal speed, in this context, refers to the maximum safe speed at which a vehicle can turn on a curve without the assistance of friction between the tire and the road. The advisory speed plates help drivers to maintain a safe speed that allows them to navigate the curve or turn effectively. For example, if a curve has an advisory speed plate indicating 30 mph, it means that it is recommended for drivers to maintain a speed of 30 mph or below to safely navigate through that curve without relying on the friction between the tires and the road.