I’m trying to get the value of how fast my wheel is spinning…
wheelBack.rigidbody2D.AddTorque(-rotationSpeed * Time.deltaTime);
this is the code that makes the wheel spin…
I want to add sounds and change them depending on how fast the player is driving.
thanks 
I am not sure if this is the best way, but…
Triggers, you could place a trigger at the edge of the wheel, childed to the wheel. As the wheel spins, it spins with it. Now, have another trigger that is stationary at the edge of the wheel, in the same location as the last trigger,however, it is not childed to the wheel transform.
With each rotation, one OnTriggerEnter is called.
Yeah, sounds smart… but it has limitations, because I want to go in different directions.
I need to pull out the value of how fast my wheel is rotating from somewhere.
I COULD make my own variable saying that if the key is held down, the value increments… if the key is released the value goes down… or something…
is your wheel parented to the body, if so can you get it to rotate on only one axis? if that is the case it might not be that hard to track wheel speed.
Okay something like this should work, angular velocity is given is radians, you can set it to a global variable and experiment with it.
float velocity = rigidbody.angularVelocity.magnitude;
if (velocity > 0)
{
//sound code based on velocity variable;
}