Why iron-rims are heated before putting them on the wheels of Bullock-carts?

Explanation:

Iron rims are made slightly smaller than the wheels. They are heated red hot before fixing them on the cart wheels to expand them so that they can be easily fixed on the wheels and water is poured on them to cool them. As the rims cool they contract and take the shape of the wheel and get firmly fixed on the wheels.

So iron-rims are heated before putting them on the wheels of Bullock-carts

Hope it will help :)

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