This is what both my rears looked like after last weekend auto-x. It wasn't
even hot outside. Is this an indicator of anything particular I'm doing wrong?

About the only abnormal thing on the course was a long 180 that was not
quite a hairpin but I had the gas pedal to the floor for the whole last half of
it. Basically with a 2.3 and limited slip and my setup, no possible way to spin
with foot on the floor.

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Nothin' wrong with that tire.....they will shed a little bit of rubber that forms "worms" & they'll migrate to where your camber allows them to hang on. I see this all the time on my track tires. Drive it like you stole it!

That's normal for a soft tire that was working hard.
If it bothers you, scrape it off between events. (he says, knowing how difficult that is)

yeah, thanks guys but I don't have a tool that's going to get that off without
a large amount of effort.

I'm leaving for the track in two hours - you are not alone. Nothing to worry about...

Tony

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That's exactly what you spent all that money for....Akin to music to my ears!

Overheating is apparent when the rubber starts turning blue ... BTDT

Could be rubber "worms" migrating off your tires. Some of that could be OPR. Other Peoples Rubber, their worms that detached and were on track. Your stickies picked it up. There are some battery powered, and corded scrapers you can use to peal/cut that crud off if you need to. Or as others have said, drive it like you stole it. First time I saw that on my auto-x tires I paniced- I spent HOW much for these tires and they're defective?!?!??! Some more experienced guys laughed a little and explained how it all worked. No big dealio. Go fast. Have fun.

Yeah, I actually found that the 'adhesive remover' blade for the vibrating saw tool
thing gets the excess rubber off pretty easily.

So, my tires aren't blue or ridiculously worn after 5 events (8-9 runs avg).
However, at the last event we did 6 in the morning and 6 again in the afternoon. By the 5th and 6th runs the car felt really sloppy and even though I was driving a better
line it was slower. Not 'overheating' but out of the good grip temp range of the 'A'
compound.

So, IMO the A7 is inferior to the A6 where I never noticed this. Either I should go to
the R7 or find something else maybe. Anybody looking for a good deal on used
205-45-16?

What you see is normal! thier AX tires not track tires correct ? I use Kumho and dont know much about the Hoosiers,or if you even have a choice with them... no wheel spin means your not pushing it hard enough hahahah have fun

MikeC ive seen lotsa blue tires Eddie

I can't deal with tires that get worse after the 4th run on a mild day. I'm
probably going to have a co-driver next season too. I might be able to use
the R7, or go down to bridgestone re-71r.

Do you have a pyrometer to check temps of the rubber? Hoosier can give you a temp range where those tires will stay happy. Maybe you and your co-driver just need to check temps after each run when you check pressures, and have a basic garden sprayer handy to chill things down. Insulated tire covers can be helpful too- you can make your own, black on one side to grab and hold heat on cold days, silver reflective on the other to keep heat out on the warmer days. Think the material used for windsheld sun shades you can buy at walmart. And don't let them freeze over the winter. Put them in your basement, best to be wrapped in that cling plastic you can get on rolls.

I'd hate to see you go to a less effective tire if there were ways to make these work better for you.

One of these works great, but do it before you leave the event. Waiting 24 hours makes it 2X as difficult.

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Tire pressure.

I never use the water sprayer, but tried a friend's once I was feeling the heat in the
tire that last day. It really didn't do anything. I actually don't have enough room in
the wheel well to insert it well.

It was a relatively cool day, so I think I would be in trouble in the middle of
summer.

yep building heat/pressure fast with AX tires and not checking pressures after every run will make basketballs outta them! even on a cool day....

I check pressure after every run and reduce back to my 'target'.

OK check and check what are they set at and whats normal ambient temp and how long are your course`s its all i can think might do what your describing those are very very good DOT AX tires and they all (Slicks)gather marbles when there hot

with the Kumho 205 -50-15 tire i run 22-24 in front 24 26 in back, colder days (PNW) its more to the lower PSI.but i like my car a little on the loose side and i can feel the car going away with lower PSIs ..our course`s are very tight in the 56 second time range and i like to slide the back end around the tight turns 0 over heat just normal build up...another 914 guy here runs same tires as you (slight flared fenders) and ive heard him say up to 32 PSI WOW! I would run those probable not at that PSI but they dont fit under my car not even the 205 50 15`s too wide .....so IMO its not the tires, its YOU getting faster and overcome grip factor in the way your driving! dont upset the car so much..Smooth but a little bit loose in the corners is good if you can keep the ass end hanging out there a foot or so and drive through it with the pedal to the metal Smooth = fast even if your cars not going strait and you have to counter a bit...yes strait with no slide is fastest but when you can help but slide because of your speed you then must become smooth to go faster....ask me how i know I love those things

Play with the PSI`s.. have fun and drive the wheels off that bitch

My "rule of thumb" was 40-50 AX passes and the tires are either close to or totally heat cycled out. Ignore this if you like getting whupped by some one that doesn't .
Fresh rubber is the cat's ass. Just another step in the process.......

One of these with the 'adhesive remover' type blade makes it possible to clean
up afterward.
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I appreciate all the suggestions.

I'm not doing anything but the local PCA autocrosses, and I don't need to go chucking
my tires after 30 runs after the 'best' grip is used. On the A6 I was using those for
about 10 or 11 events.

Some of the time we do 5 to 7 runs per session (half day) rather than 4. Back in
the day when I was using the Kumho, it took 3 runs before they were up to best
temp for grip, so I had only 1 shot at having a good run before having to wait 3 hours
again. On the A6 or A7 it seemed pretty good after 1 run of warming them up.
But unless my alignment is suddenly off or something, the A7 grip is worse after 4th
run.

Since I'm only in it for fun, and I mostly have to compete against myself, I'd be much
happier with a slower tire that doesn't fall off, than a faster tire that might be designed
for 3 runs before needing cooling.

At least with my streetable suspension settings, I never let the car wag too much
(and our courses are designed fast, usually over 60mph in a couple spots), it's not
easy to avoid spins. And I dislike the water sprayer thing. On tires that heat-
cycle out before the tread is gone, why do I want 8 mini-heat-cycles per day instead of 2?