Wheels:  The wheel, along with the tyre has to take the vehicle load, provide a cushioning effect (to protect against force or shock) and cope with the steering control. The wheel must fulfil the following requisite functions:
-  It should be strong enough as well as lightest in weight as far as possible. 
-  It should be replaceable. 
-  It should be balanced in both static (stationary conditions) and dynamic (moving conditions). 
-  Its material should not be susceptible to corrosion.