My mom is a long time DOT employee and she herself pumps out several million dollars worth in resurfacing contracts each year, so I know a bit more than average about roads, but what most people don't know about roads is that the speed limit isn't built for the road, but rather the other way around. The degree and bank of the curves, what material the road is made of, how wide the lane is, etc. all depends on the state's desired speed for the road.
So techically, going fast on a low-MPH road is more dangerous than pulling 75 over on a 65-MPH. Just be safe is all I'm saying