For those of you either replacing you headlights with the IPF setup or changing to PIAA's Philips Extremes, or Sylvania Silverstars or if you just want to check and re-align your OEMs here are a few measurements I've made on my unlifted stock 2008 JK X with 17 inch stock wheels and stock Goodyear Wrangler tires. I used the following link for all adjustments http://www.coolbulbs.com/HID-VISUAL-...-PROCEDURE.pdf
Headlamp center to center horizontal dimension is 37.5 inches or 18.75 inches center of lens to centerline of vehicle. The center of my vehicles lens to ground is 37.75 inches. A lifted or modified vehicle will have a different height measurement. According to the link, you will put a horizontal line or piece of tape on the vertical wall/fence/building 25 feet away from your headlights 2 inches below the lens center to ground measurement. For my JK that is 35.75 inches. To check to see that you are square to the wall/fence/building you can sight from the center of the high center brake light through the windshield etched label (center at the bottom) to your center line/tape on the far, 25 foot vertical object. Do it like sighting a rifle.This is most critical when checking center to center where the IPF's beams cutoff and begin slanting upward (refer to the link step 4
In addition, for reference, my front tires center to center are 62 inches. Hope this helps.