wheel colliders HORRIBLE PROBLEMS is this really me?

i cannot get my wheel colliders to stop going through the terrain…

i have made 2 other colliders underneath the car to make the car stay on the terrain, but
the wheel colliders still try to go through.

the wheels sit on the terrain, then when i drive the car the wheels pop down through the terrain.

i have been working on this for 3 days, and i have referenced all of the help posts. how do i stop my wheel colliders from going through the terrain?

i figured it out from the tutorial. cheers. here is the video:

you can check this video to solve the problem of wheel collider bouncing in unity5