Is the numeric speed display correct at the bottom-right of the screen? I assume it is. SNO would have let me know if KM/H speed wasn't displaying correctly.
It might help if you show me exactly what you changed on that one line in the skin.
Once we get this figured out, I will change the skin to check the speed unit and adjust the scale accordingly, so MPH will be 0-140, and KM/H will be 0-280