Why are roads particularly slippery right after it begins to rain?

Question

Roads are often at their most slippery when rain is just beginning to fall. This is because water mixes with oil and grease on the road to create a slick surface. As rain continues, the oil and grease will wash away.

Accepted Answer

Water mixes with grease and oil on the road.

Answer

Roads are naturally slippery.

Answer

Gravel gets washed to the middle of the lane.

Answer

Some tires are not designed for rain.