If you go to a real mill yard you can get joists from barns as salvage or even milled new to create this type of structure. Remember people still create barns and animals have a significantly larger point load(one foot) than a vehicle tire does.
If you go to a real mill yard you can get joists from barns as salvage or even milled new to create this type of structure. Remember people still create barns and animals have a significantly larger point load(one foot) than a vehicle tire does.