A funny thing happened to my brakes at the race track

[2012-Boss]

I'm afraid I'm going to need MUCH bigger tires. :-\

What are you running for tires and hot pressures?

 

[Mad Hatter]

Thats the next step.... dreaming of 315's all around. But the wheels are a too much $$ at the moment

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[ArizonaBOSS]

Thats the next step.... dreaming of 315's all around. But the wheels are a too much $$ at the moment

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https://www.amazon.com/gp/product/B00CZCDRW4/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[Fabman]

What are you running for tires and hot pressures?

295/30/18 R7's and 39 psi cold (about 50 psi hot with nitrogen)

Some folks with significantly lighter/lower powered cars were telling me to run them down in the 25 psi cold area.
I called Hoosier and they said a for a 4000 car/40 psi cold so that's roughly where I am. (39 psi cold)


I asked them about running them softer and they said:
"People think these are slicks....they are not. They are DOT tires and have to be run at a much higher pressure."


The temps were very even the first time out on these tires and I haven't checked them again but you can see the wear on the tires all the way across and even over the shoulder more than I'd like to see so softer doesn't seem like a good idea.
If you look at the rating on these tires in that size the car is much heavier than what the tires are rated for.
The fastest laps are usually the second or 3rd lap and then they start to get greasy and slow down, so that is consistent with tires that are being over worked. The car handles great until they get hot and then it gets looser and looser and was barely driveable by the end of the day. I passed on the very last session because although I could still run at a fairly fast pace I was driving beyond what I consider safe and as I responsible racer I removed myself from the track.


I'd love to hear opinions....remember, this is a very heavy/big hp car-not a 3400 pound 325 hp spec mustang.

 

[Fabman]

Thats the next step.... dreaming of 315's all around. But the wheels are a too much $$ at the moment

Sent from my SM-G900M using Tapatalk

335's or 345's

 

[ArizonaBOSS]

295/30/18 R7's and 39 psi cold (about 50 psi hot with nitrogen)

Some folks with significantly lighter/lower powered cars were telling me to run them down in the 25 psi cold area.
I called Hoosier and they said a for a 4000 car/40 psi cold so that's roughly where I am. (39 psi cold)


I asked them about running them softer and they said:
"People think these are slicks....they are not. They are DOT tires and have to be run at a much higher pressure."


The temps were very even the first time out on these tires and I haven't checked them again but you can see the wear on the tires all the way across and even over the shoulder more than I'd like to see so softer doesn't seem like a good idea.
If you look at the rating on these tires in that size the car is much heavier than what the tires are rated for.
The fastest laps are usually the second or 3rd lap and then they start to get greasy and slow down, so that is consistent with tires that are being over worked. The car handles great until they get hot and then it gets looser and looser and was barely driveable by the end of the day. I passed on the very last session because although I could still run at a fairly fast pace I was driving beyond what I consider safe and as I responsible racer I removed myself from the track.


I'd love to hear opinions....remember, this is a very heavy/big hp car-not a 3400 pound 325 hp spec mustang.

FWIW, I run my A7s and R7s in the low 20s COLD, shooting for 30 hot. This is on a 3400-3500 lb car including driver and fuel, 315/30/18 on all four corners. This works really well for me, for both sustained performance during a session as well as wear over the tread. I understand this is contrary to Hoosier's recommendations. My general rule of thumb is that if the tires are getting greasy or going away towards the end of the session, the car is being over-driven, or the starting pressures on the tires are too high, or both.

You might try mid-20s cold and see how that works out.

@blacksheep-1 has already published a body of knowledge on tire temperatures, pressures, and logging.

Also it would be great to run a 335 or 345 tire on these cars but you're not going to be able to do that with stock fenders/sheetmetal.

 

[Fabman]

FWIW, I run my A7s and R7s in the low 20s COLD, shooting for 30 hot. This is on a 3400-3500 lb car including driver and fuel, 315/30/18 on all four corners. This works really well for me, for both sustained performance during a session as well as wear over the tread. I understand this is contrary to Hoosier's recommendations. My general rule of thumb is that if the tires are getting greasy or going away towards the end of the session, the car is being over-driven, or the starting pressures on the tires are too high, or both.

You might try mid-20s cold and see how that works out.

@blacksheep-1 has already published a body of knowledge on tire temperatures, pressures, and logging.

Also it would be great to run a 335 or 345 tire on these cars but you're not going to be able to do that with stock fenders/sheetmetal.

What pressure would you run if you added 500 pounds and a few hundred HP to the car?
I'm aware of what it takes to get those wheels on the car and I'm not thrilled about doing it, but if it must be done I am capable.

 

[Mad Hatter]

My Buddies and I recently got the rep for Hoosier tires down here in Chile. Had to bring down our tire costs some how!! Two of them run Zl1's with with 295/30-19 and 315/30-19 R7's Both are at about 535 Hp at the wheels now and very very heavy. They Find that the best times are at 40 psi hot. Any lower then that and the sidewalls get corded in no time as they roll over.

 

[Fabman]

My Buddies and I recently got the rep for Hoosier tires down here in Chile. Had to bring down our tire costs some how!! Two of them run Zl1's with with 295/30-19 and 315/30-19 R7's Both are at about 535 Hp at the wheels now and very very heavy. They Find that the best times are at 40 psi hot. Any lower then that and the sidewalls get corded in no time as they roll over.

That's what I'm seeing too, sides rolling over.
I started at 36 psi cold and it was terrible.
Tire temps were cold in the middle front and rear.
I went up to 38 and then 39 and temps were even across and the car felt better.
The car basically makes too much HP for these tires at this weight.
Its hard not to spin them on corner exit and I am very careful with throttle control.
I may have to knuckle under and add anti-squat (and unfortunately roll steer).
However, I am listening to input...love to hear more of it. Hacking up the body work is not very appealing to me.

 

[2012-Boss]

Your hot pressures are too high, and I am aware of Hoosier's recommendations. The R7 simply sticks better with less pressure than they recommend in my opinion.

Depending on ambient temps, with R7s I start with a cold pressure of approximately 25 degrees and shoot for a hot pressure of 36 PSI. My car is heavier than ArizonaBoss, and I would definitely try lower if my car weighed less.

You are running nitrogen, so you will not see quite the pressure gain as I do with compressed air. Try starting with around 30 psi cold. The tires will not be fun for the first few laps and you will need to stay off the curbing to make sure you do not cut a tire down. But, once you build some heat, the pressures will come up and the tire will grip.

 

[Fabman]

Your hot pressures are too high, and I am aware of Hoosier's recommendations. The R7 simply sticks better with less pressure than they recommend in my opinion.

Depending on ambient temps, with R7s I start with a cold pressure of approximately 25 degrees and shoot for a hot pressure of 36 PSI. My car is heavier than ArizonaBoss, and I would definitely try lower if my car weighed less.

You are running nitrogen, so you will not see quite the pressure gain as I do with compressed air. Try starting with around 30 psi cold. The tires will not be fun for the first few laps and you will need to stay off the curbing to make sure you do not cut a tire down. But, once you build some heat, the pressures will come up and the tire will grip.

I see a theme developing....sounds like the consensus really is disregard Hoosier.
Okay, you have convinced me. I will comply. (Kevin will be piddling in his shoes when he reads this)
Since this is a track day car, I typically only get about 6 or 7 laps at a time.
I hope it doesn't take too long to get them up to hot pressure.
I'd hate to be pulling off the track just as the tires come in.


Anybody else agree or disagree?

 

[Mad Hatter]

actually one of the ZL1s is now running square with 295/30-19 P100 slicks that where on sale a while back at hooiser. I was surprised to see him keeping right up with another zl1 with 295s and 315s in R7. Was a great deal at US$120 a tire. Too bad they are all gone.

Maybe the new S100 slicks would be worth trying?? They seem to have a stiffer side wall??

What size rims were you running??

 

[Fabman]

actually one of the ZL1s is now running square with 295/30-19 P100 slicks that where on sale a while back at hooiser. I was surprised to see him keeping right up with another zl1 with 295s and 315s in R7. Was a great deal at US$120 a tire. Too bad they are all gone.

Maybe the new S100 slicks would be worth trying?? They seem to have a stiffer side wall??

What size rims were you running??

18x10 at the moment.

 

[ArizonaBOSS]

I am going to S80 slicks for the final event of the year and will report back afterwards. S100 might be better for the heavier car. TBD.

 

[dabossinnne]

For my last HPDE I ran a new set of R7s, 295/30-18 on 18x10 F14 wheels. Ambient temps that weekend in late Aug were in the mid 70s during the AM sessions and rose to the low 90s by mid-afternoon.

FWIW, right about 40 PSI hot is where they seem to feel/stick best on my Boss. I started out at 35 PSI cold in the AM sessions and was seeing consistent 40-41 PSI hot pressures on the front tires, 38-40 on the rear and the tires felt great for the duration of each session. In the early afternoon session as track temps heated up, I started to see more in the 42-44 PSI hot range and felt a bit of greasiness toward the end of the session. So, after tires cooled back down before the next session I let out a few PSI and got back it to 40 PSI hot after the following session. Again, no greasiness and the tires felt great.

One thing about Hoosiers, too, is they tend to like A LOT of neg camber. -3 to -3.5 deg is not too much.

 

[Fabman]

I am going to S80 slicks for the final event of the year and will report back afterwards. S100 might be better for the heavier car. TBD.

S80/S100?
Are these Hoosiers or something else?

 

[Fabman]

For my last HPDE I ran a new set of R7s, 295/30-18 on 18x10 F14 wheels. Ambient temps that weekend in late Aug were in the mid 70s during the AM sessions and rose to the low 90s by mid-afternoon.

FWIW, right about 40 PSI hot is where they seem to feel/stick best on my Boss. I started out at 35 PSI cold in the AM sessions and was seeing consistent 40-41 PSI hot pressures on the front tires, 38-40 on the rear and the tires felt great for the duration of each session. In the early afternoon session as track temps heated up, I started to see more in the 42-44 PSI hot range and felt a bit of greasiness toward the end of the session. So, after tires cooled back down before the next session I let out a few PSI and got back it to 40 PSI hot after the following session. Again, no greasiness and the tires felt great.

One thing about Hoosiers, too, is they tend to like A LOT of neg camber. -3 to -3.5 deg is not too much.

Thank you for sharing your experience with us. I am definitely going down with the pressures.
Camber I have right in that ballpark. 3 1/4* with 3/16's toe out.

 

[ArizonaBOSS]

S80/S100?
Are these Hoosiers or something else?

These are the latest generation Hoosier slicks. Hoosier's contingency program is great; if they cancel it or amend it in 2017 (due to their buyout by Continental) I will likely look into Yokohamas as I will be able to get some discounted pricing there.

 

[DocB]

R7 315s on a 3625 lb. car with fuel and driver.
I started out with Hoosier's recommendation of 36 lbs./100 lbs. of car. We saw 44 lb. even hot all around after adjusting 1-2 lb./tire for track configuration.
Tire temps were perfect across the tread on each tire.
I realize that all this also depends alot on suspension set-up. My car is just an old 4.6L 3V, but set-up to Trans-Am specs.
This was my new set-up for the last race weekend of this year. Was still getting used to the new feel of the car, and left at least 5 seconds on the table from the old set-up.
For me, Hoosier's recommendation is working out just right, shooting for 44-45 hot on a heavy Mustang.

 

[Fabman]

This shits getting old....