Hydroplaning can occur at any speed whenever a road is wet. While higher speeds increase the risk of hydroplaning, vehicles traveling at lower speeds are at risk any time there is at least 1/10 of an inch of water on the road.
Hydroplaning occurs when a car's tires pass over a wet surface and are unable to displace enough water on the road to establish traction. This causes the car to skid and slide, giving the driver minimal control over the vehicle. Vehicles traveling faster than 35 miles per hour are more likely to experience hydroplaning, so it is best to travel at slower speeds in rainy conditions. Keeping tires properly inflated also helps reduce the risk of hydroplaning.