I've been trying to fix this problem from the beginning, with limited success. Over the past 2 years, this has been my journey in my quest to fix this problem. For reference, my car is a 2017 that I took delivery on in July 2017. 245/40/18 PS4S tires.
My first alignment from the dealer was a complete disaster, they had it aligned to specs from the wrong model & it was VERY wrong. As others have said, don't count on dealer alignments.
I then took it to a reputable local shop, but they didn't have a lot of experience with this car & without much to go on at that point in time, we took a guess. That alignment was front toe in .11, rear toe in .15. Not only did it not fix the problem at all, it made the car push badly.
After driving it for a while on the previous settings & doing a lot of reading here (with so much more info on the issue), I took it back & chatted with the tech. We settled on 0 toe all around. While tramlining is far from cured on my car, these settings have made the most difference & improvement. Push is gone now as well, it's far more neutral & balanced.
Other things that I have noted or tried:
- Worn tires make the issue worse, new tires are noticeably better.
- Driving in track mode with ESC fully disabled does help some on my car, but it's still a problem.
- PDC - tried to get the dealer to turn it off (8/2019), but they couldn't find a way to do it. We talked about the issue & they did say that it's a notorious car for that issue.
I'm at the point that while it's improved (probably by about 50% if I had to throw a number at it), it's not good enough. I'm not expecting perfection, it will likely always be twitchy. But I think there is a lot of room for improvement without expecting perfection, & based on all of my reading, I've decided to install KW/Litchfield suspension w/camber plates on it next spring. This should fix the tramlining issue & bad ride all in one shot.