Originally Posted by oldrcr

The small amount of axle threads that stick out beyond the wheel nut, after you have tightened your wheel onto the axle, can catch on walls or other objects if you brush up to or run into those objects. When that little bit sticking out grabs into the barrier it often pulls the suspension apart on that side of the car. If you cut that lille bit off, usually with a rotary tool (dremel or other) and a cut off wheel or grinding stone, you will lower the chances of causing damage.
It really does make a difference.