A sharp curve ahead carries an advisory speed plaque below the warning sign. When should you slow to that speed?

Why C is correct

Braking shifts weight onto the front tyres and eats grip that the steering needs, which is exactly the trade you cannot afford once the car is already turning. The advisory speed on that plaque assumes you arrive at the corner already slowed, so the deceleration has to happen while the wheels are still straight and the tyres have their full budget available. Doing it in advance also leaves you somewhere to go if you misjudged the radius: ease off and you still grip, whereas braking mid-corner invites the rear end to step out. Practically, slow in a straight line, turn in smoothly, and pick up the power gently on the way out.

Why the other options are wrong

A. Only if another vehicle is coming the other way

Oncoming traffic is irrelevant to how much grip your tyres have. A curve that carries an advisory sign is tight regardless of what is coming the other way, and waiting for a reason to slow means discovering too late.

B. In the middle of the curve, once you can judge how sharp it is

By the time you are mid-corner you have already committed to whatever speed you brought in. The tyres are using most of their grip to turn the car, so asking them to slow it as well is how people end up wide in the oncoming lane.

D. As you exit, to steady the car

Braking on the exit addresses the one part of the corner you have already survived. Whatever problem exists was created on entry, which is where the speed needed adjusting.

On the road

Descending a canyon road, the advisory plaque reads 35 mph and the driver ahead is doing 55. He arrives at the apex too hot, lifts off sharply in the middle of the bend, and the car washes wide across the centre line. The driver behind him, who braked on the straight, takes the same corner easily at the same indicated speed.

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