There are MFGRs claims about frame strength that are not entirely true. Our Carriage 5er boasted 3/16 wall.(.188) 2x6 Turns out 3/16 was only used in the front portion, under the load over axle portion was 1/8 wall (.125)
Yes we bent the frame there while following their load recommendations because of a massive (unmarked construction bridge ) bump in the road. A spendy fix. It also tore out the rubber morryde equalizers
I belatedly determined the thinner wall tubing by the radius of the corners of the tubing. When rectangular tube is formed, the wall thickness creates a more square corner depending on wall thickness. It does not take an engineering degree to see the 50% increase in strength from the difference, or the maybe $20 in cost to them and the extra 50 # to make a frame that can take all the road may throw at it.
So look at the frame. If you see any portion that looks different, like squarer corners on tubular, or narrower or thinner flanges on I Beam frames. Question it. they are lighter, thinner than the more radiused corners of heavier tubing.
