TYRE seems to be VERY optimistic when giving the travel time, I suspect it just uses the speed limit rather than real travel times,
fwiw Tony, i've never used tyre or google to estimate times/timing, whether for a trip or a Sunday run. Apart from traffic/size of roads, there are too many variables such as fuel stops for some every 120 miles etc...
So i tend to use approx 40mph as the average speed , and then add in the time for fuel/pee/coffee/lunch etc...if the roads look tight on street view, then i might bring that down to 35mph.