What i found out to be more of a true measurement a while ago, is measure at the front of your running board, from the ground to the bottom of the running board, then measure back at the end of the running board torwards the rear and you should have a lower number in the front.
Our path also gives off the look that the rear end is lower than the front, because the front fender is higher in the body than the rear.
you can see what i mean by the red line i edited onto my car below:
by following that one indent on the cars body line, you can clearly see how much higher the front body styled fender is and it also gives off more of an illusion that the rear is lower.