Swagman rack...
 

I'm planning to buy a bent around Christmastime, am trying to do a bit of pre-planning, and have a question for anyone that has a Swagman XTC rack.

What size is the square tubing that the wheel loops mount on?

I already have two hitch mounted racks. Rather than spend the money for a third to carry my bent, I can buy a pair of wheel loops for 40 bucks and add the length of square tubing to one of my existing racks. I just need to know what size tubing to buy.

Thanks!