The steering angle set-up allows you to configure the maximum and the minimum angle for steering, and also the way that the car will steer at some certain speeds.
In the EDIT mode will be presented an angle/velocity graph where you can adjust the steering behavior at different velocities.
Adjust the ratio well enough to be able to turn into the slowest bend on the circuit and take care not to have a very great angle value for a high speed to avoid losing the grip.