We are dealing with compressive strength only in this situation because if you put the bar in tension it would mean that the strut towers were flexing outward, and that would be bad. The tensive strength is dictated by what size thread you chose to use. Obviously if the walls were drilled and tapped to within a very close proximity of the OD of the bar, then they would pull easily (but you probably know that). Next, I do not recall anyone making them out of tent poles...but I know of two made from very beefy round stock aluminum.....that look alot like the one shown here..... :p
