Question

Why a truck or a bus has as a much wider tyre?

Answer 1

The truck and motorbus have wider tyres with respect to the property that "more the area ,less the pressure." As the area is more the pressure will decrease , so there will be less need for applying more pressure to handle the vehicle.

Answer 2

a truck or a bus has a much wider tire , to not to sink into the road ( mud).if a truck or a bus has a much wider tyre the pressure applied by the truck or a bus on the road is reduced .