Tip like the things go the easiest on the wall:
1. Matching hole 8mm drill (possibly with a smaller drill pre-drill).
Completely, as provided to shim 2. Insert dowels through the holes on the wheel holders and so the anchor assembled carefully with a hammer into the hole in the wall drive.
3. When the wheel holders suspended by the anchor plan and without distance to the wall, the screws of the plugs, tighten carefully (do not overtighten).
Check!
Oh yes. Better never to get the plugs only into the holes and then get turn the screws to the wheel holders to the wall. ;-) Tip from dummy!