A motorist checks the pressure in her tyres before starting a journey. After she has driven 50 km, she checks

again and finds that it has risen.

a. Explain in terms of energy transfer and the behaviour of particles why this has happened.
b. What happens between the area of contact of the road and the tyres when this happens?

These are my answers below. Are they correct?
a. As the motorist drives, heat energy (which results from kinetic energy) cause the air particles in the tyres to move more rapidly. This results in an increase of the force applied to the tyres which produces an increase in pressure inside the tyres. This increase in pressure causes an expansion of the tyres.

b. The area of contact decreases, because the air which is now at a higher temperature will rise.

b the area of contact decreases because the effective diameter of the tire has increased due to the increased pressure and in no longer deforms as much due to the weight of the vehicle

b) is not correct.
The area of contact does decrease but it is related to a)
As the pressure is higher, and Force = pressure * area
then the area in contact with the road becomes smaller with increasing pressure.

It does not have anything to do with the temperature directly.