When tuning transmission, you can see the 6 gears i a list and at the bottom you can see the final drive. There are the gear ratios on the left but then there is a slash and the right number is something like 90 or 300 or so. What does that number mean?
It is closely related to the speed, though propably would be if there was no aero or something like that.
Some very long gear setups would read 700 and higher but top out at 450km/h.
It can be used as a rough estimation for most road cars, but nothing beats driving for actually testing the settings.