Wheels come with two different surface textures, stoneground and smooth. Stone ground surfaces are pre-broken in, which makes breaking into slides less difficult. Smooth surfaces usually have a glossy finish and provide maximum grip.
Up close roads have a jagged and rough surface. The top of these surfaces have a variation of contact points. Looking closely, a smooth surface wheel lays flat against the pavement. This creates more contact points between the wheel and the road. This causes more resistance, which means more grip. Stoneground has a rough surface very similar to the road. The contact points are inconsistent and less frequent, meaning less resistance. This allows the wheel to slide easier.