I'd like more info on what you've got the tires sitting on on your trailer. Is that box under them just to lift them up above the fenders? Or do you have a bit of storage going on under there?
I'm planning to just lie my tires down in two stacks of two on the front end of the trailer (looks like same HF trailer) for now to keep it simple. But I'm always looking for better ideas.
Thanks,
-Mike
EDIT: tire tie downs look like maybe this?
https://www.homedepot.com/p/Erickson...9160/303421789