That 1" rise per 12" of ramp is correct. I am told that the full set of regs are not that lay-man freindly to read.

I guess where I wanna interject is: the style (that #%$& bump) in doorways and where you must open/close doors can be a subtle barrier that is particularly feindish with a lap fulla groceries. So, a flat landing at the top of the ramp big enough for your ride and an opening door is not overbuilding. Its a luxury you will wish you had if you don't build in it.