Yes that is a stock sized tire, and I agree with GopherBaroque: you don't have to over-build, just don't under-build. I myself did under-build a little when it came to the hinges and I'll explain.....the hinges are actually bolted like this to the body:
On the prototype (see pic I posted of the purple two door), I actually had under-built more than on version 2.0. I only had two bolts per hinge; the ones on the right side. This was not good as it let the body flex terribly and would pull the unbolted side of the hinges away when the carrier was swung out, warping the body even more. When I did it this time (re-fabed new hinges), there are some "reinforcements" within the body that, well I'll be honest, by pure dumb luck met up with where a few of the mounting bolts went....some of the bolts were a PITA to get tightened (I actually still have a box wrench stuck inside the body somewhere I can't reach), but they hold good. I would, however, suggest (to others as well as myself) following GopherBaroque's suggestion of reinforcement.....before I start really getting off the road with this (or getting larger tires after the lift for that matter), I'll for sure reinforce it.....not sure how at the moment, but I'll get it figured out.
The "latch" is rather quite simple. I twisted (to go from the angle of the support in the carrier to the horizontal latch) and welded a small piece of flat steel to the tubing and drilled a hole in it. The piece on the rear hatch is simple too: it's a rear bumper mounting bracket from a late 80's D***e Ram van (the rear chrome bumper/roll pan on the pic with the prototype was the bumper from the same van, but cut and welded to not be as wide)....with some more dumb luck, the bolts attaching that to the rear hatch also went through some reinforcement in the body...to close it, I simply swing the gate shut, and drop in a hitch pin....no problems at all....if you want, I can get some close-ups of the components
If I were to redesign this in the future (which is likely), I'll end up using a tube bender to make it smoother instead of cutting all my angles and welding every joint (only option I had here), welding on lug bolts for an explorer so I have the same size lug nuts on the carrier as the rest of the vehicle, and putting the mounting plate a inch or 3 higher. Other than that, I love it!
