Can't be bothered posting code correctly, but you still want us to help you change it? I'll pass.
JimboZA:
Is this the kind of thing you mean?
Yes, it is finally!!! 
I change the input potensiometer with Read_Rpm and it's ok! Thank you very much!
Hi everyone, I haven't posted on my topic for a while.
Updates...
Currently i am working on the 'looks' of the dash and improving it.
Soon you will see the progress I have made with the led's and gauges.
I have received my Speedo/Tacho Head and have just got to get around to fitting it.
When I get some time I will post some pictures so you can see how everything has moved on.
Good luck to Adam164 with your project and I cant wait to see some pictures, Sorry If I haven't been reading but what game/simulator is your project for?
Steve
Here is my latest update:
It's the same project for OMSI, like Gazz. The difference is that because I don't have the tachometer, I thought about showing the RPM (or velocity) with LEDs. I am gonna upload video as soon as possible.
Congratulations for your project!
oK, I hope to see a video of your project soon, As of mine, I just have the buttons left to do on mine!
Hey, i gotta say first that i bought my first arduino uno board like a week ago and i have no idea what i am doing.
Now when thats out of the way, i got a hold on some working tachometar 1314.
Spent some cash and got arduino uno board, connected it all to omsi 1.
I had to change some values for velocity and play with it till i was happy.
Right now its like this
// Gauges
void Read_Velocity(const unsigned int value)
{
tone(10, map(value,0,1250,31,521));
}
Now, anything below 31 makes the needle go crazy before stabilizing, so i am forced to go with 31.
If i change 31 for something like "-1" or anything negative, in that case my needle goes to zero while bus is standing still but every new start of the bus makes needle go crazy 1st then stabilizes.
Gazz's D92 Dashboard is showing value 0 for "Velocity", but my tachometar doesnt go to zero.
needle stays at about 1-3km/h and it can go up and down a bit, just never hits zero (unless i use negative value but then every start look a mess) and stays there when bus is still.
Is there a way to make my tachometar hit zero while bus is standing while keeping it smooth?
Thanks
PeterSmit:
Now, anything below 31 makes the needle go crazy before stabilizing, so i am forced to go with 31.
Yup. tone does not work correctly for frequencies below 31. That is explained in the documentation...
Is there a way to make my tachometar hit zero while bus is standing while keeping it smooth?
Probably.
Any idea on how to?
Your description includes "tachometer" and "km/h". The units do not match the instrument. Which is it? A tachometer or a speedometer?