I found 2 respected Forza controller players who made a video about their controller settings for PCARS 2.
aTTaX Johnson :
Super GT :
Both are quite different settings, personally I liked the settings from Johnson the most and I'm using those now. Super GT's settings feel a bit more Forza-ish where you need to do more steering stick travel to get the same result.
For the record I'm using Johnson's settings for my PS4 Pro controller as well and works fine there as well. I will probably lower that braking sensitivity even more since those DualShock triggers have such small travel.