Thought this explanation might make you feel better next time you replace the shocks.
There's much more to the story if you want more.
Quote:
An early attempt at explaining road corrugation is due to Relton [4],
who proposed that the underlying instability mechanism is a “relaxation
oscillation,” caused essentially by stick-slip dynamics. According to this
view, a moving wheel pushes grains ahead of it. The grains pile up in front
of the wheel and form a heap. When the heap grows large enough, the
wheel sticks momentarily, and then slips, running over the heap and leaving
it behind as a ridge. For a given uniform speed, this stick-slip process will
be fairly periodic, and so will generate equidistant ridges.
A di erent picture was provided by Mather [2], who argued that the origin
of the road instability is the bouncing motion of the wheel, caused by random
irregularities on the ground. When the bouncing occurs, the car is projected
upward along a certain angle and is airborne for a brief time. When it then
strikes the ground, the car creates a crater and the motion then repeats
itself. According to this picture, it is not the piling up of grains ahead of
the vehicle that is responsible for the instability, but the impact stress of the
vehicle on the ground. The wavelength of the resulting corrugations will be
determined by the competition between the typical distance the car flies over
the ground and the size of
the crater generated by the impact stress, which
should in turn depend on the hardness of the ground and the relaxation time
of the ejected grains. Mather’s picture is similar to other surface instabilities
involving granular materials, in particular the ripple patterns in wind blown
sand [5, 6, 7, 8], where ejected grains are carried away by the wind and
land in a place far from the ejection point. In such a nonlocal model, what
sets the wavelength of the ripple is the ratio of the flux of the grains to the
appropriately scaled saltation length, i.e., the distance that an ejected grain
is carried by the wind.
Credits to Booth & Hong of Lehigh University PennsylvaniaCarpe Diem