I think Alex was just kidding....
I have no discussed this with mods but it is pretty easy to figure out:
Tier 1 is forest road type stuff where 4x4 is probably needed but air down / disco isnt. Slow pace, learning, getting to put your vehicle in 4x4, lots of stops.
Tier 2 is like most off road parks EXCEPT the crazy trails as mentioned by drich like Rathole. This is where the big guys and beginners can mix, ride seperate trails but be at the same park (or ride the same trails depending on group size). 4x4 LOW, air down, disconnecting the sway bar all would be a great idea, lockers, off road tires, lift, armor, ect all would be better.
Tier 3: You should have a trailer, a rig you don't mind taking body damage on, armor, lockers, driver skill, parts, skills to fix those broken parts the list goes on but the normal DD / weekend warrior rig isnt going to make this ride without a lot of work.