65mph is my cruising speed. I don't like going over 70; I can, i have, but it isn't my sweet spot. So, for me, 65 is safe. Trucking schools use to teach that once over 63mph you are no longer in control - the truck is; not sure what modern driving schools teach; technology, and drivability have come a long way.
On today's interstates/expressways/speedways/etc., you know, the ones with speed limits of 70+, I consider anything UNDER to 61mph to be UNSAFE.
Lately I find in metro areas going significantly slower than most traffic is even more of a hazard in that folks come up on them too fast and end up aggressively braking. So at slow speeds you become a hazard if traveling too slow.
My biggest pet-peeve about driving on interstates are the bozos who decide that even with little to no traffic they have to drive in the middle lanes of highways with 3+ lanes. And those bozos are barely doing the speed limit many times (especially the RVers). Trucks do it but waaaayyy to many RVers do it. While I can understand staying out of the right hand travel lane when many exits/entrances are close together, I just don't get it when there is clear traffic and few on/off ramps. I consider those people unsafe but mainly poor drivers.
