I don't follow how you came up with the speed units for your premise.
Flipping this about a bit...
Normal biped character speed is 50.
Average human walking speed is about 5 kph (3 mph). So perhaps speed is 10*kph? Speed at 220 would then be 22 kph (13 mph), average running speed for world champion men's marathon runner. This is a low estimate, as sprinting can kick speed up to 30-40 kph (20-25 mph).
If 220 = 130 kph by your calculation and only 22 kph by my calculations, straight forward fly speed of 50 kph by your calculations would only be 8.5 kph and diving speed of 75 kph would be about 13 kph by my calculations. I guess dragons are held aloft by magic and the known Istarian world is really, really tiny.
But it's much bigger in gnome units. :-)