Wheel spacers come in different sizes, and every person has different reasons to install them.  Some just do not want their tires to rub against the body of their vehicle, while some want to have big tires, while some want a more vivid look with tires placed far from the car. The extent of the difference can only be noticed after the placement and the type of wheel spacers you have used. If you have gone for the one with a thickness of less than an inch, there will not be much visible difference.  However, if you go for a spacer with a thickness of more than 2 inches, you can see how your wheels are now placed far out of the body of your vehicle.