Describe how an iron tyre is fitted onto the wheel of a train.

The tyre is a hoop of steel that is fitted around the steel wheel centre and a groove on inside diameter of a flange face. The diameter inside is machined to be slightly less than the wheel diameter at the centre on which it is mounted to give an interference fit.

Through controlled temperature heating of tire.

Explanation:

Tire is fitted around the steel wheel center. Tire undergoes the process of controlled heating up to particular temperature which causes tire to expand and when the tire cools down the retained shape is fitted into the groove. This tire is held in it's place by interference fit. Interference fit is also known as the press fit.