Final answer:
Tractor wheels are wider than motor car wheels to distribute the tractor's weight over a larger area, reducing ground pressure, increasing traction, and preventing the tractor from sinking into soft soil, particularly important for the heavy and varied work in agriculture.
Step-by-step explanation:
The wheel of a tractor is made wider than that of a motor car to reduce ground pressure, which improves traction and prevents the tractor from sinking into soft soil or mud. Wider wheels distribute the weight of the tractor over a larger area. This reduced ground pressure is essential for agricultural vehicles that must operate on a variety of terrains, including loose soil in fields. Moreover, the larger contact area provided by wider wheels increases the friction between the tire and the ground, which is beneficial for the heavy work tractors are designed for, such as pulling or carrying heavy loads. This design is crucial for maintaining traction and stability during farming operations.