I am going to be using this trailer for hauling a total of four ATVs, three motorcycles, a Jeep, and a Dodge Challenger (not all at the same time obviously).
The swiveling D-rings are likely the weakest tie down points on the trailer, because all they have is a 1' square steel backing plate on the bottom side of the trailer, and they are not hooked to the frame cross members at all. There just wasn't anyplace to put them where they would function best, and still be bolted to a frame cross member.
Each row of e-track is bolted to frame cross members in twelve places, and also has another 44 1-1/4" lag bolts holding it to the trailer decking (a total of 112 bolts holding down the e-tracks).
There are also four short sections of D-track that are bolted to the trailer decking, and are adjustable mounting points for a set of Track Star wheel chocks that are used when hauling the motorcycles.
I plan on using the e-track and the swiveling D-rings to tie down the motorcycles and ATVs. The clips for the e-track and the swiveling D-rings themselves are rated at 6,000 lbs. The e-track isn't going anywhere, but even the less impressively mounted swiveling D-rings should be strong enough for the ATVs and motorcycles. I will only use the pockets in the rub rails along the sides of the trailer for tieing down the Jeep and Challenger.
2014 Grand Cherokee Laredo: 2" Eibach lift, 265/70R-17 BFG KO2's, 17x9 KMC Addicts