Tire chains are fitted to the tires of a vehicle in order to provide more traction when driving through snow and ice. Tire chains are typically applied to the drive wheels on the vehicle where traction is needed most. Using chains is effective, due to the fact that when the tire rolls over the chain, the weight of the vehicle rests on the chain, which pushes into the snow or ice in order to gain traction. Driving with chains greatly decreases fuel economy and the speed at which the vehicle can operate. The maximum recommended speed while travelling with chains is around 30 MPH.
There are many different sizes of chains which fit many different sizes of tires. Using chains that are an improper fit can be dangerous and may cause damage to the vehicle and its tires. Tire codes have been created in order for the owner of the vehicle to be able to buy chains that match the vehicle's type, tire width, tire height, and rim size. Tire chains can damage the road surface quickly, therefore, tire chains are illegal in some areas.