Many semi-trucks' front tyres have spikes on the side for no apparent reason.

Semi-trucks often have metal spikes or spike strips mounted to the side of their front tyres.

Tyre chains, sometimes known as snow flaps,

are a type of vehicle accessory that helps increase a vehicle's grip and traction on icy or snowy roads.

They also help the truck driver keep their footing when the road gets slick from turning or rain.

The metal spikes embedded in the truck's tyres provide traction,

allowing it to maintain a firm footing regardless of the road surface.

They improve handling in turns and increase stopping distances on wet roads.