Why do motorists waste fuel if their car tires are under inflated?

Motorists waste fuel when their car tires are underinflated due to the increased rolling resistance that underinflated tires experience when in contact with the road surface. Rolling resistance is the force that opposes the forward motion of a tire as it rolls, and it is caused by the deformation of the tire as it interacts with the road. The degree of deformation is greater for underinflated tires, which leads to higher rolling resistance and consequently, reduced fuel efficiency. The increased rolling resistance creates greater stress and friction, leading to an increase in energy expenditure to push the underinflated tires during normal driving conditions. This wasted energy results in poorer fuel economy, causing motorists to use more fuel for the same distance travelled compared to appropriately inflated tires.