Super Strutter

I am thinking of using Metal super struts to make a rack that I can mount in my garage.

I want to use it to store the chipboard window covers for hurricane season. The question I have is would this be to much weight for the rafters to hold? They are 2X10 rafters, as our game room floor is located above the garage. Is there a certain weight limit that I can use as a guide? I don’t want to cause the floor in the room above the garage to sag over time.