Dirty track tyres

I have done dozens of track days at this track and noticed car not turning in as usual and oversteer. Also intermit vibrations. About 3 secs a lap slower. Checked pressures. All ok. Noticed a lot of rubber build up across the tyre. (MPSS on 430).
The pic was taken a few drives after the track day. The rubber deposit was twice as bad at the track, btw. It was everywhere.
We were in a pm session and the am session was race cars, radicals (also world time attack cars so prob very soft tyres) shredding marbles everywhere.
Never seen it stick like this before. It usually cleans off as you circulate. It really has become part of the tyre and cannot "pick off".
I am assuming this was the problem. My contact patch must have been very messy. How do you handle this at the track? Are there files for this? Was thinking about a burnout for the rears but what about the fronts?
Like I said, I just have never seen it do this before, so will blame the time attack cars.
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I've had that happen (felt vibrations from the tires and had sticky rubber debris stuck on them). I peeled them off by hand and then ran some hard laps and some more came off so it was a little bit better. It was still on there after the track day was over and the car handled poorly so I just got new tires as they were too beat up.

 

My MPSS look similar, although more uniform across the entire tread. Are you suggesting this is other cars rubber?

 

I think so because I have done same track, same tyres before without ever seeing this much excess rubber and I have previously been able to pick any excess rubber off.
Car felt terrible all day. Could not shake off those excess beads of rubber.
Come to think of it, a few other drivers were also complaining of unusual lack of grip but I didn't take note of their tyres.
Will try the Sport Cup2 next anyway.

 

Comes off when running at decent speed. Those tires not bad at all. My tires never look that good.

 

agreed, the harder and hotter you run the tires the more the tires are going to get cleaned off of the pickup. You will get a lot of this running off line so if you are getting out of the way to let a lot of cars pass then that is where you are getting the rubber pickup.

 

That is definitely "klag" from other tires, very common especially on tracks that aren't swept a couple times a day. I've had some pretty stout vibrations from it also, usually if i'm forced offline, but it always burns off. Some tracks, like Watkins Glen, my tires look like new when I come in. Others, LRP being one, always loads me up with crap as their cleaning equipment is rudimentary at best..

 

Hot laps should remove the bulk of built up rubber, but another alternative is a heat gun and a wide paint scraper.

https://www.youtube.com/watch?v=PG2xsK8ji78

 

Thanks for the info. Should have thought of that!
As I said, the rubber normally comes off on clean laps but this one particular day it just would not come off so I will try the heat gun.