Safe at What Speed?

When the posted limit is 65 mph, how much over that can you comfortably go? My old boss said a state trooper stated up to 10mph over the limit is safe from getting you pulled over for speeding. I doubt that, but what is ok?

Here's news (via the T-D) for southside commuters:

"The Virginia Department of Transportation is raising the speed limit to 60 mph on Chippenham between about a half mile south of Midlothian Turnpike and Route 895, the Pocahontas Parkway."

I don't travel that way much anymore but it always felt hard to stay at 55mph before on that stretch of road. Though the ever-present speed traps helped.
One other thing: These type of stories affect are daily lives much more than we speak about. Marriage license specialty plates will get more attention but really, how many more people's lives are changed from this. Yeah these stories seem small and mundane, but after my stint covering planning commissions I know this is where it's at.