Added a sample scene for ya. It's pretty simple.
Just add an FSM to the gameobject you want to align.
Add the wheels to the FSM as gameobject variables.
Set the wheels array count in the action to the number of wheels you're using and add the wheels gameobjects to the list.
You can use the layermask option to add as many layers as you want to be treated as ground.
If your wheels are static in your mesh, like in my case, you can use empty gameobjects aligned to the wheels and parented to the vehicle body instead.
Let me know if you have any trouble with it