The problem here is the way pneumatic trail works. I heavily rely on mechanical trail, as that tends to give a lot of feedback if the rear steering it, which gives you enough feeling of the rear tires slipping. Pneumatic should be the tire slip setting, but it turns the FFB off entirely once the game determines give give past peak grip. There is no progression in the drop off and it does it too soon.
Having a bit of pneumatic can be useful for telling when the car is understeering, because the car loses some ffb and you still have mechanical trail feeding you information on the rear of the car. Too much pneumatic though, and it turns off ffb when the rears loose grip too, leaving you clueless to what the car is doing. And then of course, the ffb snaps back on as well, meaming if you are the edge of grip, the ffb can start turning off and on in a binary fashion leaving you confused entirely to what the car is doing.
I run a 3 to 1 ratio of mechanical to pneumatic. K1Z Batdca, the fastest wheel player I’m aware of and also one of the fastest in the game period, runs a 4 to 1 ratio.