Actually, one shouldn't even tighten these two tiny screws, as they only serve to hold the brake disk in place when you install the wheel. The wheel bolts are the ones that take all the load, and these two screws are covered by the wheel, so they won't come out even if left loose.
What really hurts is to break a wheel bolt. Yes, you can do that, even by turning a lug wrench with your bare hands. Source is me and the takeaway from the story is to never lubricate wheel bolts.
