Why does the vehicle with a flattened tyre stop sooner than the one with inflated tyres?

QUESTION:

Why does the vehicle with a flattened tyre stop sooner than the one with inflated tyres?

ANSWER:

Due to flattening of tyres, area of contact increase which leads to increase in frictional force. Because rolling frictional force between the surface and tyre is proportional to area of contact. Area of contact increases for flattened tyres. So rolling frictional force increases and the car will be stopped quickly.

QUESTION:

Is it necessary that a mass should be present at the center of mass of any system?

ANSWER:

No. It is not necessary to have some mass at center of mass of the system.

Eg: For bangle or ring center of mass is at its center but there is no mass at center of mass.