I finally had my alignment done after a bunch of track days, the first time since purchase. (i know, shame on me :-). No surprise on the "old" street alignment (-1.4F, -1.6R Camber, 0F/.35R Toe, 8.1 Caster).
My Cups(235/305-19) lasted almost forever with even rear tire wear and front outside/middle wear, no inside wear and 12 track days until I got a nail in the rear... and bought four new ones.
Compared to the past, the car drives like a dream, easier turn-in, earlier power roll-on, faster exit. I have now -1.9F, the most it would go without doing anything else, and -2.0 in the rear, everything else unchanged.
The bad news is that I severely wore off the center of the (right) front tire with quite a bit of wear on the outside with the inside tread block still "untouched".
The outside half of each of the two center blocks are "shaved off" towards the outside to the wear bar in one long track day (160 miles). Part of the problem is probably due to too much pressure. It was cold (for CA) at 50 degrees but the front air pressure still got to 36 (instead of my normal 32/33), at least in one session. Those also were brand-new tires (2 months old and very, very fresh...) and my "break-in" might have been insufficient. I just drove to the track (75 miles) and then started.
But I'm mostly worried about "no wear on the inside" (and reversely too much wear on the outside) which I think is due to NOT ENOUGH camber in the front.
I understand from some of you more experienced folks that shims is the way to go, rather than rotating hats etc. up to maybe +/- -2.5 camber. I asked a couple of shops but none wanted to tell me what thickness of shims would be best for my situation. Any experience out there? SunCoast has 1,2.3 and 7mm. My Porsche dealer strangely enough only lists 5mm shims. I don't want to overdo it since I still drive to/from the track (freeway) and thought -2.5F/-2.0R would be a good target?

 

You need to get a base line measurement first than get the shims.

Each car is different.

Find a shop that knows what they are doing and they can do it for you.


Try BRRacing in Los Gatos

 

Sorry, Fabryce, for my ignorance but what do you exactly mean by "base measurement"? The Porsche dealer did the alignment and I have all the numbers, some of them are in my post. What else is there? All I'm asking is on what the best size is to go from -1.9 to -2.5? Is this so complicated? I don't want to drive my car around town for people to give me "numbers". There's got to be a theoretical, statistical or "average" number that one can use. Like if I want to go from -1.9 to -2.5 I need this many millimeters etc.
What am I missing?