i think it would be better, when you enter the pit, there popups a screen where you can input if you want the tyres to be changed (front and back)
and there u can choose, how much fuel you want to be loaded.

when u pit in, (and presses the speed limiter)
a box popups, with a top down view of the car, all 4 tyres are grey, and got a number in it, front left = 1 front right = 2 and so on.
u press 1 and 2 ( the tyres changes color from grey to green)
and the rear tyres stay grey, because u don't want them to change.

and than there will be a box for the fuel, for example number 9 than the fuel indicator get highlighted, and you can fill in a number, u just have to type in 40, so then the car will be filled to 40%.

this way you can doe everything with the numpad (when num-lock is on :P)

i really hopes this will be implemented.