Traction for 4x4 trucks driven in muddy conditions is best improved through the use of mud tires that are appropriate for such conditions. It is possible to further improve traction with suspension tweaks, traction devices and proper driving techniques.
As with all cars, the tires of a truck are its only points of contact with the surface it drives on, so they are the most important place to start when attempting to improve the truck's traction on a given surface. Other traction modifications to a truck cannot function at maximum efficiency if the tires are not suited for the driving conditions at hand.
Mud has different thicknesses, depths and impurities, such as gravel or sand, all of which demand different tire designs for proper traction. Narrow mud tires are best suited to slick or watery mud on top of a harder surface, as they exert sufficient ground pressure to avoid hydroplaning on the surface of the mud. On the other hand, thicker mud demands thicker tires to help maximize the surface area of the tire. It is possible to increase the surface area of tires for thicker mud by lowering the tire pressure by 10 to 20 pounds per square inch.