Well, the wheels hold absolutely an important space whether it is about a skateboard or a longboard. This is because each wheel has a different size and thickness and is used for different purposes.
So, while you are looking into the wheel design there are two primary things: durometer and diameter. The former is the thickness of the wheel while the latter is the size of the wheel. Hence, you need to make sure that the purpose of the board is compatible with the wheel size and thickness.