They are bicycles known as Fat Bikes, whose tires are much thicker than normal bikes and that allow cycling on difficult roads such as snow and sand. With the low pressure tire, the rate of adhesion to the ground increases.

The purpose of wide tires is to spread the rider's mass over a larger area and provide much more traction than a standard tire size. With fat bikes, you can ride on snow and ice without fear of losing your balance.  

Snow, winter and difficult roads… If you have a Fat Bike with you, none of them will be able to stop you from now on.