I think that if your not liking the rake you have then maybe add some trim packers or put some bags in the rear springs. It looks like you have a reverse rake, (tail sagging)? But like you said it's hard to tell.
Take a measurement, and post some numbers for us. It's pretty much agreed by most that a " center of hub, to fender) is the correct way to measure, or at least the most accurate one can get, you should read somewhere in the low to mid 20's.
There is a ton of information on suspension set up and really, it's all so overwhelming when trying to search a specific need, but if you look at the threads in the top of the 3rd gen category it has a master thread that can maybe help you out.
FYI, I'm kinda in the same boat you are, just not lifted yet. I don't wan to go up to 285's because of weight and just plain stress on the components up front, but you can go with the 255's and be at a happy medium. If you go to tire rack and look up the specs on a particular tire you want, you can find all the good information like weight, height, width and of course price, it's actually a good resource for determining what route you want to go.
Good luck!
