Track weekend postmortem (tire question)
 

I finished a weekend at Thunderhill East and have noticed a lot of tire wear on the shoulders. Track conditions were 90+ degrees outside, 95+ toward end of the day. It's hard to tell in the picture, but it appears the tire is almost meeting the tread at the edge when there is still at least 6/32" in the middle. The material near the outer edge also seems to be very worn. I also noticed after a session that there were several patches of medium grey chunks of some material on each tire. Not sure if they were bubbles, but they are gone now.

Link to pictures on imgur

Tires are Michelin PSS 225/45R17. Camber is -1 square, 0 toe in front, -.21 degrees toe in rear. In total I have used them for four track days, a few autocross events, and 5k miles driving. Cold pressure was previously set to 35 PSI, but I noticed 3mm wear past the front shoulder, so I increased front pressure to 36 PSI, which seemed to have brought wear right to the edge for this weekend.

What does this wear pattern mean? Do I need to replace as soon as tire touches tread at the shoulder? What do the grey chunks on the tire indicate?

Honestly it's called.. You used your tires. Without a lot of camber this car will wear down the edges. Rotate front to back, etc.. Try to get more camber if possible.

That's pretty normal, with some understeer wear, and minor overheating.

Add camber

Our cars are really hard on the shoulders on performance driving. Lack of negative camber and a MacPherson strut suspension. It sucks.

I really wish they went double wishbone up front. Better static and dynamic negative camber would help even the wear a ton.

Nowhere to put long enough control arms with the boxer engine, I agree it's much better though.

I'd rather have the front suspension from an EF civic.