Ok here it goes.
The hitch does not leave a whole lot of room for the spare. I am not sure about a 315 tire. My stock tire is not against it, but it is close. Now you can push the tire forward a bit before you crank it all the way up so it may work, but not sure.
The stock hitch is a class IV hitch, but it is a weak one at that. I had two problems with it. The fact that it is only connected to the ends of the frame, with the downward force I did not see that being very strong. The second is the round tubing the stock frame uses. I was in construction for years and never saw a building built with any type of round tubing for structure support.
I do not have pictures of how it bolts up, but can tell you. It bolts to the ends of the frame like the stock one. It bolts to the middle of the rear crossmember underneath the stock bumper. It also bolts to the frame farther forward towards the front of the truck. This farther forward mount gives it more support from the twisting tension of the weighted hitch. Just a stronger setup all around.
For all those who are towing overweighted in any perameter, including hitch weight. If you have any type of serious accident, even if it does not involve having too much tongue weight, the police will check everything. When they see any portion of the weight capacities being violated it will become an "other associated factor" in the cause of an accident. Not a good thing. I know this because I am an accident investigator and was trained to do all the above.
I don't want to have any part of fault when an "accident" happens.