HSSSTOY
Enthusiast
...What psi is a good start for a Track day! Thanks.
ACR Track Tire pressure .
- Thread starter HSSSTOY
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HSSSTOY
Enthusiast
CCBrian,
What is your hot psi reading?
What is your hot psi reading?
I was also at Infineon and I started at 25F/28R. I got to 32F/36R but my tread temps were a little cool. I was measuring in the 120's after a nice easy cool down lap. I would've expected the tire temps to be a little higher - even with the cool down lap. It's not my home track so I didn't bother with getting HOT tire temps, maybe I should've.
After Infineon I went to Thunderhill and I ran the same pressures, 25F/28R and they went to 33F/37R on a much cooler day. Tread temps made it into the 140's, again with a (long) cool down lap.
Hey CCBrian - it was nice to meet you!
Greg
After Infineon I went to Thunderhill and I ran the same pressures, 25F/28R and they went to 33F/37R on a much cooler day. Tread temps made it into the 140's, again with a (long) cool down lap.
Hey CCBrian - it was nice to meet you!
Greg
Hey Greg, sounds like you had fun-it was great meeting you guys too. Greg was running I believe the smooth track setup as his car was sitting lower and was faster through the turns. Depending on the setup, both of these numbers are good starting points. It was the first time out in the car for us, and a new track to him, so we were both in a learning curve. But as Greg can attest, in the street legal groups we ran , no one was faster than the ACR's. And there were serveral GT-R's, a Scuderia 430 Ferarri, and many ZO6's to name just a few.The main thing though is everyone behaved and went home in one piece.
Tom Shapiro
Enthusiast
I start my Sport Cups a bit higher at 29 all the way around. On 80-85 degree days at the Autobahn CC in Joliet last summer, my hot pressures stayed pretty constant at 36/34. That track is 3 1/2 miles long with 21 turns.
ACR steve
Enthusiast
I think it all depends on how fast you run the car. ( as close to its potential as possible) a good rule of thumb on a heavy car like ours is that it will make from 10-15 lbs hot. Always try and get a good hot reading and continue to bleed them down during the day. 35-37lb is probably the ideal pressures ( everyone has there own driving style and there for pressures vary)
I run with slightly higher inside temps. When accelerating the rears generate heat on the inside of the tread (because of camber) and when braking the front and rear generate heat towards the inside of the tread (again, camber). This is in addition to the heat generated by cornering.
We spend hours looking at tire temps on my oval car! It's waaayyy more complicated.
Greg
Brad04Mamba
Viper Owner
At Buttonwillow in February, the Archer guys were saying they were seeing the best results at 38 hot. So I started at 29 all around and couldn't get them above 36. Sorry forgot to add, these were the Cups on an ACR
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Brad04Mamba
Viper Owner
Also, when are you guys planning to go back to Thunderhill. I love that track and want to get there at least once this year. I can't do the 11th
BennyBad
Enthusiast
here in s.fl. usually temp. in mid 80's running cold 26R and 28F with nitrogen and they heat up to 33R and 35F. tire temp after a 2 mile cool down lap around 150.
HSSSTOY
Enthusiast
Ambient temp is around 10-12 degrees C, stock 08 ACR factory settings, on a short track 3 km...to be around 38 psi hot.... what do I need to start with ! Front/ 25, 29....30, Any one wants to venture a guess!
You'll kill tires unless you add some neg camber. Your outside tire temps will be too hot and your inside temps too cold. Even lowering the car will add some neg camber - and you can do that easily in your garage.
I think 38 is on the high side especially with factory camber settings. But to answer your question, 29 psi - if you run with fatory alignment settings. Plus it's always easy to let air out.
Maybe start with 30 then check on a hot tire. Bleed the tire down to you target of 38psi. When the tire cools check the pressure then you'll have a decent idea where to start with cold pressure next time.
Greg
HSSSTOY
Enthusiast
Thanks Greg......as you suggested all factory settings for now...29psi.
Nabil
Nabil
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Bruce,
Kumho Ecsta V-700s like about 34 to 35 psi hot.
Cold tire pressures will vary at each track. When I ran them, I started them at about 28 front, 27 rear. A bit Lower on the left side of the car if the track is full of right turns, like Willow Springs.
Check them hot after the first session and adjust from there.
Dan
Kumho Ecsta V-700s like about 34 to 35 psi hot.
Cold tire pressures will vary at each track. When I ran them, I started them at about 28 front, 27 rear. A bit Lower on the left side of the car if the track is full of right turns, like Willow Springs.
Check them hot after the first session and adjust from there.
Dan
SoCal Rebell
Enthusiast
I found at Willow Springs the Pilot Cups on an ACR did not heat up as much as all the other Vipers I tracked with PS2s or Hoosier R3S06s. They only rose about 7psi instead of 10psi like on my Gen 2. Also the rears got hotter then the fronts in the ACR, it may be the downforce. Also with a -1.7 front alignment I corded the fronts on the 4th track day, also the front wear was very uneven with alot more tread on the inside with the outsides cording. Driven hard the ACR need at least a -2.3 on the fronts maybe more.
CaptainDavid
Enthusiast
Michelin says to start at 28 or 27, but do not allow the pressure to exceed 38 Lbs.. I suggest running nitrogen
