Stop in for a cup of coffee
they would fill those suckers with foam and rotate them to the scraper can and get new drivers. Once in a while I would see a hole big enough to put your head in and all you could see was that foam. All they had to do back there was support the weight of the can and it's dirt.
I don't know if they still do it, but the big dirt movin' spreads I ran into used foam. When the drive tires wore out to slicks on the scrapers