I don't know if this sounds right but I was told that in order to see if the springs have sagged you measure from the center of the wheel (center cap) to the bottom of the flare. Now is there a set height in needs to be on 33's. I have an 06 TJ. I did not take any measurements before and after
"The world will know, that few stood against many"
You will need to know the factory height, and adjust for your lift and tire size. I don't remember what it is for a wrangler, but I know for an xj it's 17.0 inches in back and 17.5 inches in the front.
99 XJ Sport
3" Skyjacker lift
31 x 10.50 General Grabbers