CDL General Knowledge Practice Test

Driving on a wet road with worn tires significantly increases the risk of hydroplaning because worn tires have reduced tread depth, which limits their ability to channel water away from the surface of the tires. When a vehicle is traveling on a wet road, especially at higher speeds, the presence of water can create a barrier between the tires and the road surface. Well-maintained tires with sufficient tread can displace the water, allowing for better traction. However, when the tread is worn, the tires are unable to effectively expel water, resulting in a loss of contact with the road and, subsequently, hydroplaning. This condition makes it difficult for the driver to steer, brake, or accelerate effectively, which can lead to accidents. In contrast, driving on a dry road does not create the conditions for hydroplaning, while maintaining a consistent speed does not inherently increase the risk. Finally, using low-beam headlights in fog is unrelated to hydroplaning, as it pertains more to visibility rather than traction on wet surfaces.