have R7's changed? disturbing grooving
10-01-2018, 04:57 AM
#136
Rennlist Member
Thanks Matt.
Too bad another Kiborked thread wasting so much time reading drivel. Hope he goes on his meds soon.
Ive been doing it wrong trying to stay under 32 and that makes me start under 20 because I don’t want to stop and waste laps to get out and bleed down.
Starting to low contributes to overheating and the damage in OP pics perhaps.
I have had the same.
I can’t get 16 sessions out of the tires and they are completely cooked anyway from overheating once I get them 32+. Perhaps better to run higher and manage the tires better.
I plan to deal with the tires going off as opposed to give up the first 3 laps to get them up carefully.
Going out at 26 will make me come in on lap 4 to bring them back down to 32 and maybe I can run them higher because then they don’t overheat as much?
no,you are NOT "overheating" your tires starting lower... that is some funny nonsense right there peter! what you are saying is that you are overdriving the tires, and if you dont overdrive them, they wont overheat. If this is your problem, then, this is true.
People Always mock what they dont understand. dont worry ,you are not alone "trackcar" gooof! if you are looking at where R7s and R6s are fastest, they are in the 30 to 32psi range, and this is from not only my testing but those that are running the track records in SCCA... ALL of them over the past 15 years..
go back to this post of one possible idea of why there could be a problem with the tires in specific use cases and reasons why. https://rennlist.com/forums/racing-a...l#post15322615
Last edited by mark kibort; 10-01-2018 at 02:18 PM.
10-01-2018, 06:27 AM
#137
As a reference point, I drive a C6 Z06 that is a NASA TT1/TTU car. Full aero, suspension etc.. I am normally on R7 or A7s. I haven't seen this wear pattern as shown from the OP, and I just got done with 3 full days at WGI with NASA on R7s. Tires were mounted and balanced on a Hunter Revolution machine with no issues.
As another reference point (which may not apply here and so I apologize as it is unrelated to Porsche): Us poor Vette guys do not run a Hoosier DOT to anywhere near 40psi+ and expect to be quick. They are greasy and slower at/above around 35 psi no matter what Hoosier says (as they say this to avoid complaints of poor tire wear and to reduce the risk of a product liability claim). A race tire need only survive a race and not multiple weekends of DE. Most of the Vette guys start out at 20-24psi cold and end up at 30-34psi hot (ideal) depending on conditions, location and other variables. So it is easily a 8-14psi rise in pressure over the course of a race, depending on many variables. Vette guys don't care whether optimal performance is at 20psi, 30psi or 40 psi. Just what is the quickest. And that number hot is 30-34psi (max) on a Hoosier DOT based on literally years and years and years and years and years of testing. The issue is well understood (at least for Vettes running 315/345 or 295/335 on a 3200lb car with full aero running sub 2:00 at the Glen as a reference).
I will now run these same R7s for DE with PCA at WGI for the next two days and I expect to be a few seconds off pace which is fine for DE, but they are good enough for another few days. And during DE I will start at 27psi for the first session and bleed down throughout the day to keep temps around 34psi max hot.
As another reference point (which may not apply here and so I apologize as it is unrelated to Porsche): Us poor Vette guys do not run a Hoosier DOT to anywhere near 40psi+ and expect to be quick. They are greasy and slower at/above around 35 psi no matter what Hoosier says (as they say this to avoid complaints of poor tire wear and to reduce the risk of a product liability claim). A race tire need only survive a race and not multiple weekends of DE. Most of the Vette guys start out at 20-24psi cold and end up at 30-34psi hot (ideal) depending on conditions, location and other variables. So it is easily a 8-14psi rise in pressure over the course of a race, depending on many variables. Vette guys don't care whether optimal performance is at 20psi, 30psi or 40 psi. Just what is the quickest. And that number hot is 30-34psi (max) on a Hoosier DOT based on literally years and years and years and years and years of testing. The issue is well understood (at least for Vettes running 315/345 or 295/335 on a 3200lb car with full aero running sub 2:00 at the Glen as a reference).
I will now run these same R7s for DE with PCA at WGI for the next two days and I expect to be a few seconds off pace which is fine for DE, but they are good enough for another few days. And during DE I will start at 27psi for the first session and bleed down throughout the day to keep temps around 34psi max hot.
10-01-2018, 12:43 PM
#138
Rennlist Member
As a reference point, I drive a C6 Z06 that is a NASA TT1/TTU car. Full aero, suspension etc.. I am normally on R7 or A7s. I haven't seen this wear pattern as shown from the OP, and I just got done with 3 full days at WGI with NASA on R7s. Tires were mounted and balanced on a Hunter Revolution machine with no issues.
As another reference point (which may not apply here and so I apologize as it is unrelated to Porsche): Us poor Vette guys do not run a Hoosier DOT to anywhere near 40psi+ and expect to be quick. They are greasy and slower at/above around 35 psi no matter what Hoosier says (as they say this to avoid complaints of poor tire wear and to reduce the risk of a product liability claim). A race tire need only survive a race and not multiple weekends of DE. Most of the Vette guys start out at 20-24psi cold and end up at 30-34psi hot (ideal) depending on conditions, location and other variables. So it is easily a 8-14psi rise in pressure over the course of a race, depending on many variables. Vette guys don't care whether optimal performance is at 20psi, 30psi or 40 psi. Just what is the quickest. And that number hot is 30-34psi (max) on a Hoosier DOT based on literally years and years and years and years and years of testing. The issue is well understood (at least for Vettes running 315/345 or 295/335 on a 3200lb car with full aero running sub 2:00 at the Glen as a reference).
I will now run these same R7s for DE with PCA at WGI for the next two days and I expect to be a few seconds off pace which is fine for DE, but they are good enough for another few days. And during DE I will start at 27psi for the first session and bleed down throughout the day to keep temps around 34psi max hot.
As another reference point (which may not apply here and so I apologize as it is unrelated to Porsche): Us poor Vette guys do not run a Hoosier DOT to anywhere near 40psi+ and expect to be quick. They are greasy and slower at/above around 35 psi no matter what Hoosier says (as they say this to avoid complaints of poor tire wear and to reduce the risk of a product liability claim). A race tire need only survive a race and not multiple weekends of DE. Most of the Vette guys start out at 20-24psi cold and end up at 30-34psi hot (ideal) depending on conditions, location and other variables. So it is easily a 8-14psi rise in pressure over the course of a race, depending on many variables. Vette guys don't care whether optimal performance is at 20psi, 30psi or 40 psi. Just what is the quickest. And that number hot is 30-34psi (max) on a Hoosier DOT based on literally years and years and years and years and years of testing. The issue is well understood (at least for Vettes running 315/345 or 295/335 on a 3200lb car with full aero running sub 2:00 at the Glen as a reference).
I will now run these same R7s for DE with PCA at WGI for the next two days and I expect to be a few seconds off pace which is fine for DE, but they are good enough for another few days. And during DE I will start at 27psi for the first session and bleed down throughout the day to keep temps around 34psi max hot.
low pressure and running too hard or incorrectly in warm up could be one. but you are exactly right. the guys here running the fastest are running lower pressures than recommended. If you want to run 25-50 heat cycles at 44psi, have fun. I don't think anyone would think you would ever be close to the fastest (all other things being equal) But i can assure you , all the racers in the top 15 in any class running these tires at the runoffs, will be running pressures you have experience running and no one gets more than( 7-10 heat cycles ) and expects top performance because they are 1-2 seconds off at that point.
10-03-2018, 05:07 PM
#140
Rennlist Member
01-19-2019, 09:45 AM
#142
Three Wheelin'
Same thing happened on my 991 GT3. Severe delamination type wear on inner rear tire edge, I’m assuming it’s RWS toe-in related, but it sounds like there’s maybe something wrong with their QC.
https://rennlist.com/forums/991-gt3-...ge-wear-2.html
https://rennlist.com/forums/991-gt3-...ge-wear-2.html
01-21-2019, 03:57 PM
#144
Rennlist Member
01-21-2019, 06:43 PM
#145
Something has changed. I'm +2 psi from where I was 6 months ago. I have run A7's since before they were A6's exactly the same way ran the A6's. I started with hoosier when they were the S04's. I had a real bad time running at Sonoma Runoffs on new HooHoos. I ran 2 races T2 & T1 same car and barely got through race with zero tire wear and gobs of pick-up like I was running off line. Center bead of casting flash was still there after entire races. I could have bicycled a faster laptime. 2 new sets 2 different days 2 different races same car and weight just restrictor change. Same build code on tires later 2018. Old set scrubs, early 2018, I ran practice and 1 qualy were faster than the new tires. I never had tires act like this before. My guess was I did not get enough heat in tire. I ran sonoma tires +2 psi at Homestead miami and +2 psi same set at Sebring last week and tires came to life with normal wear and good pyrometer readings. Darn now I got to break out the pyrometer and gather data to dial in this new compound. I really think they have changed something.
01-21-2019, 09:10 PM
#146
Rennlist Member
Something has changed. I'm +2 psi from where I was 6 months ago. I have run A7's since before they were A6's exactly the same way ran the A6's. I started with hoosier when they were the S04's. I had a real bad time running at Sonoma Runoffs on new HooHoos. I ran 2 races T2 & T1 same car and barely got through race with zero tire wear and gobs of pick-up like I was running off line. Center bead of casting flash was still there after entire races. I could have bicycled a faster laptime. 2 new sets 2 different days 2 different races same car and weight just restrictor change. Same build code on tires later 2018. Old set scrubs, early 2018, I ran practice and 1 qualy were faster than the new tires. I never had tires act like this before. My guess was I did not get enough heat in tire. I ran sonoma tires +2 psi at Homestead miami and +2 psi same set at Sebring last week and tires came to life with normal wear and good pyrometer readings. Darn now I got to break out the pyrometer and gather data to dial in this new compound. I really think they have changed something.
