Quite a bit especially if your tires are worn down to or below the tread depth limit.
Wet pavement increases stopping distance around 95% at 60 mph.
Dry asphalt roads
by improving tire traction for one
It notifies the driver that the road conditions are creating reduced friction between the tyres and road surface, hence, reduced traction. You'll see it on particularly wet roads, snow/ice covered roads, etc.
Asphalt roads are considered to provide the best traction for automobiles in most conditions. Concrete roads will provide better traction in high temperature areas.
This helps with the traction of the tires to the road. It helps the tires not slip or slide on the ice.
The salt will melt the snow and ice, but can really damage the roads. The Sand creates more traction and will not cause damage to the roads.
The water creates a layer between your tires and the road so your tires don't grip the road, they lose traction.
its not Well, its not "generally" put on ice, but when it IS used its put down to suppposedly increase traction and reduce slipping on sidewalks and roads.
Chains increase the surface area which increases the friction so you gain traction.
poor traction
They will work just fine as long as its only a dirt road your going on.
Road cycling is - hardly surprising - done on roads. Preferably roads that are in decent condition and with not too much traffic.