My dealer was kind enough not to drill my front bumper for me, but didn't do the rear either. Anyone know the hole size I need to drill for the self tapping screws?

 

I can't remember for sure what size, but I chose a bit that was just a tad smaller than the minor diameter of the screw. Probably something like 1/8 in. The self tapping/drilling feature does the rest.

Tighten them up till they start to strip then back 'em off a half turn.