Thought I'd post this thread because in a couple of years someone is going to ask this question and no-one will have the answers. It will probably be me trying to compare lift kits...
I've measured from the ground, across the centre point of the wheel to the lowest point on the flares - they slope downward slightly as they head from the outside to the inside of the car. Just to clarify - I didn't measure to the outside point of the flare, but the lowest point.
On a stock 2-door Rubicon with about 3/4 tank of fuel, I get the following heights:
Front: 895 mm
Rear: 915 mm