[midweSTST]

Recently completed 2nd track day with a '17 ST1. (brake mods listed on 1st track day experience post)
About a 4 mile road course with 12+ turns. 86 degree day. Couple of long straightaways
* Stock Eagle F1s (30 psi) performed fairly well again. However, last session when they got hot, loss of traction again experienced on long sweeping curves. Is this type of corner always the first to feel a lack of tire grip ?
Again, no ST heatsoak issues even on this hotter day, no intercooler needed at this point. Oil temps remained moderate.
The ST ate up a Porsche Boxster and E30 M3.
Even ran better than a 650hp Z06 considering he was experiencing the well documented Z06 overheating issues and his car was in the parking lot doing 0 mph

 

[crashmw]

30psi seems kinda low...but I am not being critical. I ran 35-36 cold.
Next time out I will be on RE760s most likely, so have no idea where to start with on those.
I will bring my stock wheels with F1s just in case the RE760s are not that good, as I cannot find anyone that has run them and provided commentary.

 

[stylo]

Hey, can you just confirm that you ran it 30 psi HOT ?

I have someone telling me to use 32psi hot on street tyres .. so that sounds about right. Have you experimented with any other pressures ?

 

[aaronc7]

30psi hot on stock alignment probably going to get you a lot of outside shoulder wear and wont be ideal for sure. 30psi cold sounds more reasonable. This isn't the end all solution, but a useful technique for day of, at the track is the chaulk a couple spots on the outside edge, and add or lower pressure as needed to make sure the tire isnt rolling over/wearing beyond the actual tread. Proper alignment will change things up a bit.

 

[crashmw]

30psi hot on stock alignment probably going to get you a lot of outside shoulder wear and wont be ideal for sure. 30psi cold sounds more reasonable. This isn't the end all solution, but a useful technique for day of, at the track is the chaulk a couple spots on the outside edge, and add or lower pressure as needed to make sure the tire isnt rolling over/wearing beyond the actual tread. Proper alignment will change things up a bit.

Interesting. I was way off... No wonder the Tires looked so good... Ie are not scribing the sidewalls...
Guess I need to bring a pump and start off much lower.

CrashMW

 

[stylo]

Interesting. I was way off... No wonder the Tires looked so good... Ie are not scribing the sidewalls...
Guess I need to bring a pump and start off much lower.

CrashMW

So you went on track at 30psi COLD but didn't check after each session ?

I'd be interested to know what PSI you track goers have used HOT and on just street tyres

 

[crashmw]

So you went on track at 30psi COLD but didn't check after each session ?

I'd be interested to know what PSI you track goers have used HOT and on just street tyres

Is the hot pressure a variable that varies depending upon the brand and model of tire?

CrashMW

 

[aaronc7]

I haven't tracked the ST so I can't comment on hot pressures...but most tires generally like mid 30s hot. You might need a little more to keep the outside edge from rolling over/wearing down, depending on alignment of course. For guys who are pretty new to it (myself included) I think the above procedure works pretty well without really digging into the weeds of pyrometer and constantly tweaking alignment settings. I'm out there to have fun. Also tires have a little triangle on the edge of the tread, this is what the manufacture defines as the end of the usable 'tread'. I use this as my point of reference.

But overheating a street tire is pretty typical and while messing with pressures can help a little, it's not going to solve the issue. You just need to take a lap or next few turns easy.

hard to see but you can see the white areas that I chaulked up, theres a triangle right there.

 

[midweSTST]

Hey, can you just confirm that you ran it 30 psi HOT ?

I have someone telling me to use 32psi hot on street tyres .. so that sounds about right. Have you experimented with any other pressures ?

Starting psi was 30 psi cold front and back. After 1st session, hot temps on rear went to 36 and stayed there all day. On fronts, went to 40+ after second session and kept going up each session. So, I bled off air on fronts just to keep hot psi at 39/40 . Started at 30 psi cold because this was a long track with long corners so there wasn't a risk of sidewall rollover as the tires warmed up. For autocrossing, I would start at 32 psi cold to avoid unneeded sidewall rollover (sidewall of tire contacting ground during cornering). YMMV

 

[Kevin]

I run 31/32 cold and it's usually 40ish by the end of the session.

 

[stylo]

Starting psi was 30 psi cold front and back. After 1st session, hot temps on rear went to 36 and stayed there all day. On fronts, went to 40+ after second session and kept going up each session. So, I bled off air on fronts just to keep hot psi at 39/40 . Started at 30 psi cold because this was a long track with long corners so there wasn't a risk of sidewall rollover as the tires warmed up. For autocrossing, I would start at 32 psi cold to avoid unneeded sidewall rollover (sidewall of tire contacting ground during cornering).

I'm worried about the sidewall rollover if I am trying to achieve 32-33 psi hot temp ... I guess I just need to put in good cold lap to get there street tires warmed up


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[loki141]

Ran, 41r/39f hot. Found it worked well on stock tires. But I like the backs a bit harder, I feel like it helps me get on the power sooner mid corner.

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[SiThlord]

Ran, 41r/39f hot. Found it worked well on stock tires. But I like the backs a bit harder, I feel like it helps me get on the power sooner mid corner.

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Try deflating the fronts more and it might not push as bad while keeping the rear loose enough point and shoot early in the corners


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