I can't find any reference to these in a search, so I thought that others with the Sport Cup 2 might find these documents interesting. It was certainly new information for me.

In an autocross this weekend, my times got worse as I tweaked the pressures downward on my SC2s so I thought I should find better guidance... and indeed it appears I was dropping the hot pressures down too far. I was also making the mistake of checking surface temperatures with an IR probe rather than a needle probe. Needle probes are strongly recommended it seems since surface temperatures can be misleading (as I'm sure many on here could have told me).

As @beez points out in a later post, this doc was for the original Sport Cup and not the Sport Cup 2. Let's delete that!
In any case, attached is a PDF document that Michelin has published on the subject or pressure and ideal tire heat ranges for the Sport Cup 2. There is a link to it on the Tire Rack site.
https://www.tirerack.com/images/pdf/...nd_Feeding.pdf

This is a link is to a similar document for the Sport Cup 2 R.
https://www.tirerack.com/images/tech...SportCup2R.pdf

And this is a link to a presentation on the PCA site that has similar guidance for the Sport Cup 2. The applicable Sport Cup 2 section starts on page 23.
https://www.pca.org/sites/default/fi...r-TTW-2018.pdf

I'll be interested to see what those with expert experience have to say with regards to the above recommendations.

FYI, I know that the SC2 isn't really the best thing for autocross, but Tire Rack says the Yokohama A052s I have on order are still more than 90 days backordered so I'm trying to stay with these for now.

 

IR probes are worthless imo.

32-34 peak psi for me.

Not sure how long you have to get them to temp/pressure.

 

I am not on the track, but I find that 30.5 F and 32 R COLD is the sweet spot for me. That equates for me to about 34 F & 38 R HOT when I am pushing the car or on a hot day. I like the higher front pressure than stated on the door jam, as it provides a little crisper front end on initial turn-in. Less than that and the car has too much lateral movement and feels sloppy. More than that and the tires start to lose lateral grip.

I have also found that the Cup 2's fall off FAST as the ambient temp. rises. I get the best grip out of the car when the sun goes down and the outside air temps are in the 60s/70s. On hot 80/90 degree days when the sun is out, I do not have as much grip.

Looking forward to trying the GY SC3 tires soon.

 

Between 32-34 hot has always worked for me as well on Cup 2s and most other tires.

 

There is what people anecdotally find works for them, and there is what Michelin/Porsche recommends. Michelin and Porsche recommend 29 front and 33 rear, regardless of operating temperature. The N1 compound is designed for this car and those pressures. Other tyres that aren't factory homologated will probably differ from this but they are quite specific about it. Our race team has had a direct conversation with Goodyear on our GT2 RS rally car, their tyres are factory homologated as well and they have told us the same thing. Nameplate pressures regardless of operating temperature is what you want to aim for.

My own personal anecdote is that all of my fastest laps have been set when the tyres were closest to 29/33. Best outcomes have been generally for me to aim for them to come up to 29/33 for the fastest lap, typically 3-4 laps into a session, then they will finish the session slightly higher than this. If you are doing a full race you want them to stabilize at 29/33, a short autox would probably start with them at those pressures.

 

Seems to me that the OP is talking about an autocross. You won't have enough time to get the tires hot. A 1 min or so run should have the cold pressures adjusted up. Depending on the OAT he may even have to spray them down a bit before each run.

 

Thanks for all of the advice!

Like @ExMB pointed out, while I've done two half-day track outings, I am mostly interested in autocross since that is the only place I'm competing for place. And I like to win While many out there with more autocross-friendly tires were spraying down their tires between runs, I decided not to since I thought the SC2s would benefit from the extra heat.

There certainly can be issues get the SC2s up to a good traction temperature for autocross in the winter and spring so that's the main reason I have the A052s on order. I'd like to get those on the car before the weather starts cooling down more making it even harder to keep the SC2s warmed up. (Coincidentally I got a message from Yokohama this morning saying "Unfortunately, we do not have an ETA for the Advan A052. We are currently experiencing capacity and supply chain issues. We apologize for any issues this may have caused".)

At this last weekend's event the ambient air temperature was showing at about 104f on the car's thermometer when I did my runs (last group). I saw the rear tires make it up to 175f on their surface with an IR thermometer but like @raymort pointed out that isn't really a good indication of the core tire temperature. Heck, I'd bet the pavement itself was 145+ (I wish I had checked!).

Maybe @TRZ06 's thoughts about high ambient temperatures were coming into play. I definitely felt a lot looser than I expected this time out and I got a little looser feeling on each run, dropping almost 0.3 seconds on each clean subsequent ~52 second run when I almost always run faster each run. Certainly not slower on each run four times in a row. (I ran the same location in April when it was cooler and got faster each run that time like I normally do)

As you can tell from the first post, I was suspecting my targeting 29/33 regardless of temperature was causing issues and maybe I was wrong to bleed them back down to that each run. But then @Reedy seems to get good results there. However, I think until I can get new tires I'll try higher pressures like @raymort , @TRZ06 and @lovetoturn recommend and those recommendations seem to be in line with those Michelin documents.

Thanks again everyone! I hope that others at least find the posted documents useful. I for one hadn't seen the recommended temperature ranges or higher pressure recommendations before.

Maybe the real issue is the tires now have 5000 miles on them, including two partial day track events and six autocrosses along with a lot of fun drives in this summer's searing Texas heat. I should have pointed that out in the first post. It could be they are just getting heat-cycled out

The wear across the face looks better and more even than I expected at this point so I think the camber I have is working okay for me. I am running -1.7/-2.3 degrees front/rear camber. I still have more tread remaining than I would have expected too.

 

I start at 28/30 cold on the track, however I did find that I have to bleed air quite frequently on a tighter track with greater frictional forces on the tires.

 

May I suggest you check out https://www.yourdatadriven.com/what-...-car-tyres-be/

I would strongly doubt that in a 60 second autocross there is any chance of getting to the temperature where you'd get maximum grip. Now it depends on the tire compound, but any street DOT tire would have to be well down the degradation/grip curve in an autocross and still be able survive a 3 hour drive across the desert @ 125F in full sun.

I've tried Hoosier autocross tires (A7 compound) on my SP3 PCA club racer. Even at summer temps (80s) they don't go over the edge in 6-10 laps at a track like Mid Ohio. The same tire in an "R7" compound (thread wear of 40) would not be optimum until at least the 2nd or 3rd lap. Both tires should be softer than a Sport Cup 2 (Thread wear 240).



Your tires would have to look like this before they got too hot:



Balance is a different issue. That is one end of the car having more relative grip than the other. The front and rear at likely at different spots on the grip curve relative to what the car needs to be balanced.

It's been a few years since I've autocrossed but I can't ever remember a time when my tires got too hot. My pressures might have gotten too high, but the temperature never was.

 

My observations are far from authorative, but my non OEM sized (and not 'N1') Cup2 seem to like around 33 to 35 front and 34 to 37 rear (psig, hot). Less than that and I didn't like the squirm and breakaway characteristics.

 

Listen to this.

 

The first PDF link in your post refers to the old Michelin Sport Cup tires (before the SC2s were introduced) not the Sport Cup 2s. Look at the tread pattern in the pictures, and the copyright info at the bottom of the last page shows 2009. I've used these back in the day, and they were great, TW rating of 80, and very much like the current Pirelli Trofeo Rs, but totally different tire from the SC2s

 

Oh no! Sorry for the misleading post. I'll go back and figure out how to edit that first post to remove the error.
Thank you!

 

Has anyone tried out the Sport Cup 2 Connect along with the app and sensors? I'd love to hear how they compare to the Sport Cup 2 if you have any experience.

With the Yokohama A052 being on backorder with no release date planned (other than 90+ days), I need to start considering alternatives. I see the Connects are in stock in my sizes. I need 20" tires due to my PCCBs so some of the other "normal" options are not available either.

 

I used the SC2 connect tires on a '15 991 GT3 on Laguna Seca a couple of years ago. I was skeptical, but they actually do work, if you do what it says. As the track heated up during the day, it kept telling me to let air out of one tire, then after another session, another tire, then a different one, after another session etc. I started to feel like the pressures were getting pretty low, but the lap times kept coming down. The whole thing, with the sensors and all is really expensive though. I can't imagine this would work with AX, with the laps being so short.