fat bike

/F AE1 T B AY0 K/
noun
  1. 1

    (winter sports) A bicycle specialized for riding on snow-covered trails, such as snowshoeing trails, cross-country skiing trails, winter hiking trails, and skiing pistes. The bikes have fat wide snow tires, similar to aviation tundra tires and trucking M/S tires, to increase traction on ice and snow.

Source: https://en.wiktionary.org/wiki/fat%20bike