What is the primary factor affecting stopping distance during rainy weather?

The primary factor affecting stopping distance during rainy weather is the wetness of the road. When the road is wet, it significantly reduces the friction between the tires and the road surface. This decreased friction means that the tires cannot grip the road as effectively as they would on a dry surface. Consequently, the vehicle requires a longer distance to come to a complete stop because the braking force is diminished.

In rainy conditions, water creates a barrier between the tires and the road, which can lead to hydroplaning, where the tires skim over the surface of the water instead of making direct contact with the road. This further exacerbates the issue, increasing the distance required to stop safely. Therefore, understanding how wet road conditions impact stopping distances is crucial for safe driving in adverse weather conditions.