Tonka Trucks: Coffee is hauled from farms (still in parchment) to the Expocaccer mill in these handsomely customized rigs. The lines running to the hubs stumped me when I first saw them in Brasil long ago. It's air pressure, controlled from the cab. When they run empty, they optimize the air pressure, as when fully loaded. The weight difference with these kind of coffee loads is so great, and gas so expensive in Brasil, that it makes a lot of sense.