Try my recommended settings for the Moza R12 to use with iRacing.
Moza Pit House Settings
Basic Settings
Steering Angle - 900
Road Sensitivity - 10
Game Force Feedback Intensity - 100%
Maximum Wheel Speed - 50%
Wheel Spring Strength - 0%
Wheel Damper - 5%
Advanced Settings
Maximum Output Torque Limit - 100%
Hands Off Protection- Off
Natural Intertia - 150%
Wheel Friction - 15%
Speed Dependent Damping - 15%
Start Point of Speed Dependent Damping - 90kmh
FFB Effect Equaliser
All EQ Points Set to 100% (Flat Line)
Base FFB Curve
Base FFB Curve - Linear
Miscellaneous
All Settings Default (Make No Changes)
In iRacing's Options > Drive > Force Feedback
Enable Force Feedback - Yes
Use Linear Mode - Yes
Reduce Force When Parked - Yes
Strength - 9.0
Wheel Force - 12Nm
Intensity - 50%
Smoothing - 0%
Damping - 0%
Min Force - 0%
Force Feedback will still vary from car to car. Some cars are inherently 'harder' to steer than others, so you might want an easy way to turn FFB up or down when switching cars. The best way to do this is within iRacing - Whilst seated in the car, press F9 to switch to the Graphics Adjustment box in the lower left corner of the screen, and tweak FFB Strength up or down.