History

• The automotive tire chain was patented in 1903, shortly after cars were invented. These devices first saw use in military and agricultural applications, but quickly spread to the open road.
  
  

Function

• Tire chains function much like the cleats on a shoe, and are used to dig into hard, slippery surfaces like ice. They can also be used in mud and snow, but don't work as well as a proper all-terrain tire.
  
  

Breaking the Ice

• The main advantage of tire chains over knobby tires is their ability to break through and dig into the thick layer of ice that covers many roads during the winter. Tire chains can increase traction by over 300 percent in icy conditions.
  
  

Tractor Trailers

• Nearly all tractor trailers carry a set of tire chains, particularly those that operate in cold, mountainous areas.
  
  

Legality

• Carrying tire chains can prevent an expensive ticket in some places, as states like Colorado and California require that chains be visibly displayed for inspection.