We are in the planning stages of building a cordwood gazebo. Planning on a gravel trench foundation after leveling the ground, followed by a rammed earth tire stem wall. What I am wondering right now is, with a stem wall like this (thinking either 1 layer or 2 layers of tires, could use some input on this as well) can we just fill the tires with gravel instead of packing earth into them? I have read some stuff on rammed earth construction and some people have expressed interest in trying with just gravel (now "gravel" that I would use is pit run, basically just a mixture of sand and clay with some stones). All we are looking for is a way to get the cordwood off the ground to reduce rot etc.. Any input would be appreciated. Thanks