X-Tech,
I think the Mid-West Farmer Junior Stockers filled the tires with Portland Cement Limestone
A little trick they used on the farm, to get better traction from the
John Deere Tractors. (148 lbs./ cubic foot)
Seems that the powder weighed a bunch, and filled nicely in one of those 7.75 x 14's.
I think the only way to get it out of the trunk, was like you you said, an engine hoist,,, or wait for the trunk panel to rot out

PC