Yes, the leak is through the sidewall of the tire.
Agree, installing tubes in those little tires would be a PITA. Getting the tire on and off the wheel is a huge hassle itself. If I must do it again, I'm going to make bar to go through the hub which can then be clamped in a bench vise. Having the "third hand" holding the wheel in place would be a help. Anyone else tried this?
A neighbor who works with larger equipment says they fill all their tires with foam. Has anyone tried this. My experience with foam in other applications is it inevitably deteriorates.
And then there's the numbnuts who designed a fork to mount a captive air tire with a valve stem which cannot be reached with an air chuck.
jack vines