Earlier quoted context omitted.
It's a bit of a tangent, but all the roads I've seen labeled 30mph or 35mph would be quite safe to take at 45. The flow of traffic is 5mph over anyway. But this is with residential roads universally at 25mph. I'm not sure what kind of road he was on.
How do you determine "safe to take at 45"? Kinetic energy increases quadratically to speed, so your braking distance is much larger and doesn't scale linearly to speed so, no, just because you feel your car can safely take those roads at 5-10mph over the limit doesn't mean it's safe, the environment dictates the speed limit, not the road conditions per se.
I look at the roads that do have speed limits of 45mph.
> the environment dictates the speed limit
Yep! And the roads I'm talking about are built in the same way with the same environment as the 45mph roads.
I'll back down my "all" to about "90%" though, I remembered a short road where 35 actually fits.
But in general, if we accept that the 45mph roads are actually safe at 45mph, then there's a lot of 35mph roads would be equally safe at 45mph.