What are Wheel Spacers for?
They are designed to make the wheels sit out farther from the axel, basically widening the stance of the wheels. It is the cheapo way to widen your car's wheels without getting new wheels or something. So for $30 you can widen where your wheels sit. They are of course, much more prone to failure and they put alot more stress on the car. I do not recommend them.
They are just spacers that you put between the rim and the hub to make your wheel stance a little wider
The spacers are put between the hub and the tire rim to move it away from the vehicle so than you can put a wider or taller tire.