I have been using my C5 for a year now and was having problems getting the setting right.
I discovered “Marvin’s Awesome iRacing App”. (Just google it) It is free and for me really improved the feel or the wheel. It has much easier to understand tweeking and even on the simplest settings it was a big improvement (you will see what I mean). You turn off iRacing’s FFB and use it.
Definitely worth a try. I spent a couple of hours on the skid pad tuning the feel. (Not really required, but worth the effort).