When considering the friction between a rubber tire and a wet asphalt road, which material property is most likely to increase the friction coefficient compared to rubber on dry asphalt?

The friction between a rubber tire and wet asphalt is mainly governed by how well the tire can “grab” the road’s surface. When the asphalt is rougher, the rubber’s tiny bumps can lock into the larger bumps of the pavement, creating more mechanical interlocking even when water is present. This increase in surface roughness raises the normal force that the rubber can apply to the pavement and thus raises the friction coefficient. For example, a tire on a freshly paved road with many small potholes will slip less than on a smooth, wet, freshly poured surface. In short, a rougher asphalt surface is the material property most likely to boost friction on wet roads.