When It Rains the Roads Are Most Slippery?

Roads are most slippery when it rains after a dry spell because oil and dirt haven't washed away. Your tires don't grip as well on oil-slicked roads, so slow down when the first rain hits. California's Department of Motor Vehicles recommends driving five to 10 miles per hour slower on wet roads.

Why is the road more slippery when it first starts raining?

Slow down at the first sign of rain, drizzle, or snow on the road. This is when many road surfaces are most slippery because moisture mixes with oil and dust that has not been washed away. ... Heavy rainfall can reduce visibility to zero. Pull over and wait for the rain to subside, or until visibility is restored.

When it rains the roads are most slippery after several hours of light rain?

Just after it starts to rain. Driving during the first half hour of rainfall is dangerous because roadways become extremely slippery when the water mixes with oil and other chemicals on the road surfaces that have not yet washed away.