Place a single layer of car tires on the ground in the shape of your building's perimeter. Scoop small gravel into the center of each tire, filling them up completely. Make sure you fill the hollow sides of the tires also.
Scoop dirt in on top of the gravel, tamping it down with a tamping pole to shift as much dirt between the stones as possible. Tamping poles are usually wooden broom handle poles with flat, horizontal squares attached to the end for packing dirt.
Place another layer of tires on top of the first. Arrange the second layer to stagger the first, placing each tire across the place where two tires touch on the first layer. Fill these tires with gravel and dirt also, tamping them as you did the first layer of tires.
Continue layering tires on top of each other to form your walls, leaving out the gravel after the third layer of tires. Use a sturdy ladder to stack them if the walls are as high or higher than your shoulders.
Stretch a tarp over the top of your structure when the walls are finished. Place tires around the edges of the tarp to keep it in place. Stack more tires on top of these in a pyramid pattern with tarps in between each layer. This makes a well-insulated outbuilding or shed with a relatively well-draining roof.