Question

Why a truck or a motorbus has much wider tyres?

Answer 1

1. The force acting per unit area is called pressure. i.e $Pressure=\frac{Force}{Area}$.
2. The pressure is inversely proportional to the surface area.
3. The larger the area, the smaller the pressure, and vice versa.
4. The truck and motorbus have much wider tyres, so that more the area, less the pressure.
5. Therefore, there will be less need for applying more pressure to handle the vehicle so that the vehicle will move smoothly.

Hence, to handle vehicles smoothly by applying less pressure, a truck or motorbus has much wider tyres.