I don't know if mine is optimal, but I have sen at 210 (don't have new software so if you do, may want to go down to around 180). FF @ 100, Sho @ 100, Dri off, ABS 95.
Also important is in game. FFB is set high at about 80%+ all settings. I have all assists off.
Wheel saturation at 45% (or 50%), Linearity at around 60 to 70%, No dead zones and 100% saturation on pedals.
Those are the basics. I think ideally if you can set the wheel at 180 degrees, then you'd set wheel saturation at 50%. Since I'm at 210, I have mine at 45% saturation.
Any other setups recommended, because I haven't cracked the top 15 in 3 races, highest qualy 13th. I am however getting a little faster each week. On the hard setting, it is challenging. Just taking the same car to Time Trial which I assume has all the upgrades, you can cut 3-6 seconds off laps easily. Just easier to drive and more stable too.