The wheel of a vehicle has several technical functions:
– it is the linking element between the vehicle hub and the tyre, of which  assures the inflation pressure too

-it undergoes to several stresses due to its own weight, to dynamics, to drive transmission and also to the brakes application

-it has also an important function of brakes ventilation when brakes are located on the vehicle hubs (that is in modern vehicles and for requirements of limitation of the hanging parts, actually almost on all of them).