For anyone's future reference, you can BARELY fit a set of Rubicon fender flares in a large Home Depot television box to ship.
If you put the front flares in first upside down, one at a time, and leave them sticking up a bit, and then squash the two rear flares together a bit and stick them angled but mostly upward, you can slide them in until you feel a pop. Rotate all four flares until they stop, and then you can entirely fit them in the small side of the box.
Fill with a crap ton of crumpled packaging paper or used wrapping paper (like from your favorite holiday or birthday celebration), slide the other box over the top, and telescope it fully shut. You can 100% get it to its smallest size. Be sure to overstuff the big center void to preclude the box from being crushed.
This creates a package that is 41x37x6 inches externally, weighs roughly 23 lbs, and is double heavy wall cardboard on 4 sides and single heavy wall cardboard on 2 ends. It's actually surprisingly tough.
https://www.homedepot.com/p/The-Hom...ure-Moving-Box-with-Handles-1001018/203339256
View attachment 292648