What driving condition typically requires the greatest stopping distance?

When considering the conditions that affect vehicle stopping distance, a wet road significantly increases the stopping distance due to reduced tire grip on the surface. On a wet road, tires can lose traction, leading to longer stopping distances when a driver applies the brakes. This phenomenon is primarily due to the film of water that can cause aquaplaning, where tires do not make sufficient contact with the road, leading to a longer reaction time and a greater distance required to halt the vehicle.

While snowy conditions also require greater stopping distances, the layer of snow can sometimes offer more friction compared to a fully wet road, depending on the specific conditions. Dry roads generally provide the best traction, allowing for the shortest stopping distances. All-weather roads, while they can provide adequate grip under various conditions, do not consistently offer the same level of traction as wet roads when it rains, making them less of a concern than the wet condition described.

Thus, a wet road is typically seen as the condition that demands the greatest stopping distance due to the combination of reduced traction and the dynamics of vehicle braking.