Hey allbeen trying to wrap my head around terrain Is it possible to make it like set Max height then as cars Race on the surface it's goes down to min height ? Like at start make Max height as corrosion happenes then stop at min height? How's that?
Often actual deformation of the surface isn't done, it would either take a very high count of vertices or extreme complex tesselation. What you can do is add marks in the terrain constructing them with a trail renderer or like the skid marks in the Car Tutorial for instance where you'd have a normal map which makes it look like the terrain is sunken down, as long as the wheels are touching the surface.
Not sure exactly what your trying to do, but Terrain Destruction allows for runtime terrain deformation.