Wheel spacers

wheel spacers do widen the quad out on the front or the back. this makes it more stable so you can take corners much faster they are the cheap alternative to a wider axle and wider a-arms just as effective just not as reliable they tend to break under extreme pressure from jumping and such.
 
for the front, they are not even close to have wider a-arms.
in the front, the wheel spaces add more bump steering.
in the rear there isn't much difference.