Umm... what kinda douchebag wrote CnR for that?
I ignore people speeding unless they are going 15 over, or around that area. I'll stop for about 13 over depending on how calls are going.
In my state, this wouldn't fall under Careless/Reckless.
EDIT (again): This wouldn't fall under Careless/Reckless unless you got 1/2 car length off of the bumper of the slow car, changed lanes quickly without using a turn signal right in front of another car who had to brake to avoid a rear end collision, and then swerved back over in front of the slow car, missing its hood with your rear bumper by about 10 feet.
Add in honking a horn, throwing a cigarette at them and flippin' them the middle finger just for comic relief.