For traction and to prevent hydroplaning on a wet road.

Hydroplaning or aquaplaning by a road vehicle occurs when a layer of water builds between the rubber tires of the vehicle and the road surface

No, Hydroplaning is not safe, because when a vehicle is in this condition, there is a "cushion" of water between the tires and the road limiting traction allowing the vehicle to skid out of control.

When your tires lose adhesion with the road it is called 'hydroplaning'

It would depend on the weight of the vehicle, the vehicle's tires and the amount of water on the road.