Interstate speeds are 120kph-ish* (75mph) standard here the speed limit actually being 112kph-ish (70mph). Everyone speeds on the Interstate here, and you can comfortably get away with 8kph-ish (5mph) over. Of course the left-lane folks tend to break 145kph-ish (90mph+) and over.
* Using "ish" because the calculator values are down to several decimal places and I don't feel the need to share that.