I had to buy a 5 x 10 because the trailer is 5 wide. $280. PT would have costed ~ $60 so metal was $220 more. Since I use the trailer for hauling construction debris occasionally on small urban jobs, I figured it would be worth the extra cost to ensure nails and screws don't fall through the cracks in the lumber.
I was curious because I want to close the center of my car trailer and have not priced it yet, I hear the tariffs are playing heck on the price of steel.
Thanks!