[Junkyardspecial]

[Stephen12ZL1]

Wingfoot is the correct term...start at the beginning of the day before track use at 28-29 and that should be perfect. If you drove to the track, start at 30 or so. Target max 36-37psi always feels best to me. At 34-35, max grip is achieved and the car feels most planted.

[TrackClub]

Originally Posted by Stephen12ZL1

Wingfoot is the correct term...start at the beginning of the day before track use at 28-29 and that should be perfect. If you drove to the track, start at 30 or so. Target max 36-37psi always feels best to me. At 34-35, max grip is achieved and the car feels most planted.

[TrackClub]

Originally Posted by GunMetalGrey

So it's the Goodyear boot images on the tire edges that are the right marker to use, not the lowest line on the edge of the tire?

I saw those Goodyear boot images but didn't know what they were for especially since they don't seem to be consistently in the same location along the edge of the tire.

Many manufacturers use such symbols as a visual indication of under inflation. Michelins have them on my Tahoe. There is no other explanation for their existence, albeit i have not been able to confirm it officially.

What Stephen said above is exactly what i do as well.
Start 28 cold, go up to 36/7 hot then bleed to 35/4 while checking for wear after each session. This is important as wear might be different due to venue, temps, track condition (green vs rubbered in), over driving a specific corner, etc.

Sometimes it is just one tire that scrubs too much. Sometimes the car may have a better balance with less or more psi based on type of venue and loads involved.
So what you FEEL as a best balance is also key.
NB tire pressure is a main tool in NASCAR as it will change the handling, especially if different pressures are used F vs R or even single corners. But that's entering a different level of complexity.

Basically 36 hot is great overall imo. 35 or 34 hot usually better but an eye on a scrub line after each session is a must to adjust up if too much wear.
Even when targeting 36 hot one should check presssure and wear after each session as often the former will continue to rise, requiring bleeding, especially if sessions are close together. Cheers!

PS this is for G3s of course. For example Nicky Bobby runs R7s and that's a completely different animal pressure wise.

[TheRealJA105]

I set my cold pressures at 28 psi, once I'm at the track and they have cooled from the drive there, per the performance supplement. The first lap after the out lap is the fastest 95% of the time. Not sure how much pressure they gain on that warm up lap, but I would guess they are only at 30-33 psi for their max grip. Lap 2 is pretty close grip wise and sometimes I can turn a quicker one, but they definitely start falling off on lap 3 then plateau and that's probably when they are at 36-38 psi. I usually never bleed between sessions because that original 28 psi cold is the key factor and the wheels retain so much heat between sessions.

[Stephen12ZL1]

Originally Posted by TheRealJA105

I set my cold pressures at 28 psi, once I'm at the track and they have cooled from the drive there, per the performance supplement. The first lap after the out lap is the fastest 95% of the time. Not sure how much pressure they gain on that warm up lap, but I would guess they are only at 30-33 psi for their max grip. Lap 2 is pretty close grip wise and sometimes I can turn a quicker one, but they definitely start falling off on lap 3 then plateau and that's probably when they are at 36-38 psi. I usually never bleed between sessions because that original 28 psi cold is the key factor and the wheels retain so much heat between sessions.

drop 1 psi for every 10 degrees of ambient temperature rise during the day.

[TrackClub]

Originally Posted by TheRealJA105

I set my cold pressures at 28 psi, once I'm at the track and they have cooled from the drive there, per the performance supplement. The first lap after the out lap is the fastest 95% of the time. Not sure how much pressure they gain on that warm up lap, but I would guess they are only at 30-33 psi for their max grip. Lap 2 is pretty close grip wise and sometimes I can turn a quicker one, but they definitely start falling off on lap 3 then plateau and that's probably when they are at 36-38 psi. I usually never bleed between sessions because that original 28 psi cold is the key factor and the wheels retain so much heat between sessions.

Ive just finished a 3 day run at Mosport and have another day to go tomorrow as part of Canadian Motorsports Hall of Fame fundraiser. If i started at 28psi and just let it be id be driving afternoon sessions at way over 40 hot. Zero doubt about it, especially (as Stephen mentioned above) ambient rises during the day (virtually always). In any case, each time i came off i was over 36 hot and had to bleed. Having said that many sessions were 30mins and sometimes only 30mins to cool down. Regardless, cold starting psi is just a guideline to get to a hot sweet spot on a FIRST run. Hot psi is by far the vital measure here to prevent overheating. A cold starting point is just that and a measure one wont see ever again during a day of running. Unless the ambient stays the same and there are many hrs in between sessions (both highly unlikely scenarios). Cheers!

[Norm Peterson]

Originally Posted by TrackClub

... Regardless, cold starting psi is just a guideline to get to a hot sweet spot on a FIRST run. Hot psi is by far the vital measure here to prevent overheating. A cold starting point is just that and a measure one wont see ever again during a day of running. Unless the ambient stays the same and there are many hrs in between sessions (both highly unlikely scenarios). Cheers!

This ↑↑↑

And maybe not just for preventing overheat. It's the pressure at which the tires are actually operating and it's those properties that matter while you're driving. Tire vertical spring rate and other tire stiffnesses vary with inflation pressure, for starters.


It wouldn't surprise me at all if the "door sticker" cold pressures account for 2 or 3 psi pressure rise in normal driving. "Cold" is simply the more repeatable condition for checking purposes.


Norm

[Jimbeau11]

Was just at The Glen weekend before last. 95 degrees ambient.
Had to drop cold pressure to 25lbs to stay below 37lbs hot.

Been a few years since I was at Daytona, but overheated everything..... Had to bleed the tires down multiple times. I can't imagine you'll have a problem getting them up to pressure.

[TrackClub]

Bingo: last 2 posts!

[Snakebt6]

Re: Daytona

I started at 30 in the front and 31 in the back and was right where the track guide says to be after a 6 lap run.

I was a pound higher on the right as I assume the banking had a lot to do with that.

Lap 6 was my fast lap and last lap in this session and had the highest heat and pressures.

[TheRealJA105]

Originally Posted by Stephen12ZL1

drop 1 psi for every 10 degrees of ambient temperature rise during the day.

This I can 100% agree with and will start paying more attention to because it is a fact. Won't need to worry about this for TNiAs, but definitely for full days and Time Trials.

Originally Posted by TrackClub

Ive just finished a 3 day run at Mosport and have another day to go tomorrow as part of Canadian Motorsports Hall of Fame fundraiser. If i started at 28psi and just let it be id be driving afternoon sessions at way over 40 hot. Zero doubt about it, especially (as Stephen mentioned above) ambient rises during the day (virtually always). In any case, each time i came off i was over 36 hot and had to bleed. Having said that many sessions were 30mins and sometimes only 30mins to cool down. Regardless, cold starting psi is just a guideline to get to a hot sweet spot on a FIRST run. Hot psi is by far the vital measure here to prevent overheating. A cold starting point is just that and a measure one wont see ever again during a day of running. Unless the ambient stays the same and there are many hrs in between sessions (both highly unlikely scenarios). Cheers!

Even if you started at 33 warm (they are staying warm for a long time which is why I don't rely on between session pressure checks) from your first session you aren't going to get the tires hotter than the last time on the track, but yes as I stated above I should be paying more attention to ambient temp. You guys are all telling me my pressures are too high, yet I haven't seen anyone with edges rolled over as far as mine?

Originally Posted by Jimbeau11

Was just at The Glen weekend before last. 95 degrees ambient.
Had to drop cold pressure to 25lbs to stay below 37lbs hot.

Been a few years since I was at Daytona, but overheated everything..... Had to bleed the tires down multiple times. I can't imagine you'll have a problem getting them up to pressure.

I'll try to pay closer attention to my hot pressures by switching to them on the console during the cool down lap and maybe learn some things (1SS no PDR problems), but it's proven these 200TW class tires fall off after 2 laps. I for one don't really care for the hot pressure at the end of 20min because the end of the session is slower for many reasons.

[TrackClub]

We will just have to disagree on this

Unless the tires cool down sufficiently between sessions, they will absolutely continue to gain pressure as their starting points will continue to elevate with each run PLUS increasing ambient (if that's the case temp wise).

Agree that pressure itself is just one measure to pay attention to. The other important one being the contact patch wear. Your car is heavier and has much more power, plus you wheel it pretty good too So it all comes into overall consideration tire management wise.

Agree on balance that ANY tire will start to fall of some after an outlap or two. But the G3 handles heat VERY well indeed. My PB at Mosport was accomplished on lap 10! (And it is a competitive time btw). So, for an average amateur hack like me, an ability to push *consistently* and error free, is proly more important than number of laps on a tire. This is assuming one does not over drive the car with wide slip angles of course. If that happens the tires will absolutely go off by about lap 3 or 4 max and will need to cool down to regain grip.

Cheers!

[TheRealJA105]

Originally Posted by TrackClub

We will just have to disagree on this

Unless the tires cool down sufficiently between sessions, they will absolutely continue to gain pressure as their starting points will continue to elevate with each run PLUS increasing ambient (if that's the case temp wise).

Agree that pressure itself is just one measure to pay attention to. The other important one being the contact patch wear. Your car is heavier and has much more power, plus you wheel it pretty good too So it all comes into overall consideration tire management wise.

Agree on balance that ANY tire will start to fall of some after an outlap or two. But the G3 handles heat VERY well indeed. My PB at Mosport was accomplished on lap 10! (And it is a competitive time btw). So, for an average amateur hack like me, an ability to push *consistently* and error free, is proly more important than number of laps on a tire. This is assuming one does not over drive the car with wide slip angles of course. If that happens the tires will absolutely go off by about lap 3 or 4 max and will need to cool down to regain grip.

Cheers!

In your experience, if you air them back down to 28psi when they are still warm, how much lower do the pressures stay in the next session? If I can gain more time I'm all about it! Perhaps I should just try something new and see if I improve, get worse, or no difference at all?