By pushing the wheels further away from the vehicle hub, they increase the track width, hence reduce body roll. This helps improve your tires’ lateral grip. The tires are more evenly loaded, which leads to better handling of the car and faster acceleration coming out of a corner. This adds more stability and improves handling even when the tire size does not change.
With these wheel upgrading components, you can create an additional clearance between your wheel and vehicle hub to get rid of its tucked look. As a result, your wheels are able to sport a wider stance and a more interesting appearance.