Chapter 5 (Basics), page 145, of “SHIFTING Into 4WD” offers this about why you scuff rocks or drop off into gullies with the rear wheels.  Tour the book.

If there is any one single thing that gets newcomers, it’s what I call wheel cheat.  Wheel cheat can cause serious paint and body metal damage.  Follow along with the drawing on page 146.  It shows the front and rear tires do not follow the same track in a turn.  Maybe you’ve pulled out of a driveway and felt the rear tires miss the driveway and plop off the curb.  Or maybe you are the type that cuts right turns too closely and scuffs the curb with the inside rear tire.  Most big trucks warn: “This vehicle makes wide right turns.”  This is to compensate for wheel cheat.

I think it’s like “out of sight, out of mind.”  We pass the obstacle (curb, driveway, rock, gully) and make our turn.  If we can’t see it, it can’t get us, but nothing could be further from the truth.

On tight, twisty trails, wheel cheat is more significant than you might ever suspect.  I haven’t measured every 4X around, but it is typically about three feet for a 100-inch wheelbase vehicle and increases with wheelbase.  That means on the sharpest turn, your rear tires will track three feet inside the front tires.  That is a whole lot of body metal, folks!  Learn and pay attention to your 4X’s wheel cheat.

The way to avoid wheel cheat is twofold.  First, approach the big metal muncher from as far away as possible.  Don’t drive right up alongside, then sharply turn.  Next, if possible, wait until the obstacle is at least behind you, and preferably directly opposite the inside rear tire, before you turn.  Now, make a sharper turn than you otherwise would.  Another way of putting this whole scenario is don’t turn
too close, too soon.

This technique also helps.  I almost feel like I am cheating because it’s so easy.  Simply adjust your door mirrors (electric, I presume) so you can see the rear tires and surrounding body metal.  Now, you no longer have to guess how close you are to those nasty rocks, particularly on the right side.  You can see them.

Until now, the wheel cheat caution has only addressed rocks, but there’s something worse!  Picture a tight, cliff-side mountain hairpin.  Visualize Mother Nature has just laid down a good storm that washed the inside of the road over the cliff.  Now picture that your neglectful wheel cheat puts your inside rear tire in the washout, off the edge and the 4X follows.  Over the side you go!  It’s important to learn about wheel cheat and how to manage it.