Question

Why are tyres of heavy vehicles kept broad?

Answer 1

Use the formula for the pressure acting on an object. This formula gives the relation between pressure on the object, force on the object and area on which the force is acting. Using this equation, state the relation between the pressure and force acting on the tyres of the heavy vehicles and reason for using broad tyres.

Formula used:
The pressure $P$ on an object is given by
$P = \dfrac{F}{A}$ …… (1)
Here, $F$ is the force on the object and $A$ is the surface area of the object on which the force is applied.

Complete answer:
From equation (1), we can conclude that the pressure on the tyres of the heavy vehicle is directly proportional to the force exerted on the tyres and the area of the tyres.
The weight of the heavy vehicles is very large and all this weight exerts a force equal to the weight of the vehicle on the tyres in the downward direction.
For the heavy vehicles to travel with desirable speed, the weight on the tyres should be minimized otherwise the tyres may undergo wear and tear and become unusable within a short period of time. This happens because the large pressure on the tyres may force the tyres downwards and release the air filled in the tyres resulting in puncture of the tyres.
If the tyres of the heavy vehicles are kept broad, then the force of weight of the vehicle on the tyres gets distributed over the surface of the tyres and the forces experienced by the tyres becomes relatively less.
This allows the tyres to carry the heavy weight of the vehicles without wear and tear for a longer time.

Note:
The students may think that the larger area of the broad tyres used may undergo larger friction and wear and tear of the tyres may occur. But the main purpose of the broad tyres used in the heavy vehicles is to reduce the pressure and hence force on the surface of the tyres.