The more research I do, the further down the rabbit hole I go. Here’s what I think I understand... In laymen’s terms, I can treat each tube as a “ I -beam” in that the top and bottom of the tube is treated like the flange on a beam. The wider the flange, the more torsional stability the tube has. The taller the web (side wall of the tube) the stronger the resistance to deflection longitudinally. So the 2x2 better for torsional forces (twisting) and the 1x3 is better for less longitudinal deflection (sag).
Now an engineer will chime in and tell me everything I think I understand...is wrong
