Skid Plates

Sooner or later you are going to drag the underside of your rig on a rock, and when that happens you are going to either be happy you have skid plates or really wish you did. I learned this the hard way with one of my first rigs when a triangular rock on the top of a berm caught on my transfer case and then rotated, cracking the housing of my transfer case.

The first areas of concern are your steering, radiator, oil pan, transmission, transfer case, gas tank, and emissions components.  Not all of these will be vulnerable in every vehicle, and if you bought an "Off-Road" edition rig you may be lucky enough to have basic skid plates already.

The stock transfer case skid on a Jeep TJ.  This is actually one of the better stock skid plates on 4wd vehicles these days, and it is adequate for moderately maintained roads, but if you high-center your rig on it then it will bend.   A bent skid plate can bind up your shifters and create vibrations in your drivetrain. 

This is the custom replacement skid I put on my TJ after I folded mine over a rock.  You can buy aftermarket skid plates for most 4wd vehicles, however if you can't find skid plates for your rig there is always the option of having them made, either by a professional shop or a skilled amature. 

If your gas tank is vulnerable then a good skid plate for it should be one of your top priorities. Nothing will end your day faster than puncturing your tank and losing all your gas, and denting the bottom of the tank  will often damage your expensive fuel pump.  Most vehicles come with a gas tank skid plate, but it is really no more than a guard against rocks being thrown up and will not protect your tank from dragging it on a rock. 

A heavy duty gas tank skid plate for the Toyota Tacoma made by RCI Off Road. I don't endorse this particular skid, however the design and strength caught my eye.

If you are willing to cut into your rig and you know a skilled welder you can actually replace the lower section of your rocker panel with a piece of rectangular steel tubing.  

A frame mounted rail doing it's job to protect the Jeep's body

Once you have the underside of your rig protected the next thing you should look at is the rocker area.  Depending on your vehicle you may have options for frame mounted "Rock Rails" or body armor.  Each style has advantages and disadvantages, and styles and feature vary greatly between manufacturers.  Frame mounted rails can be stronger and can provide a better step, but give up ground clearance.  Body armor needs to be very well designed to not pass stress upwards into the body where it can cause flexing and even cracking, but it gives more clearance.  With either style I recommend choosing a design that sticks out from the side of your rig farther than the widest point on your doors so can slide along a tree or rock without denting your rig.  What you don't want are "Nerf Bars" that are really just stylish steps and will fold if banged on a rock.