Inside corners of tires getting trashed on track days. stock car
04-22-2023, 08:35 PM
#17
Rennlist Member
Anyone else experiment with rear toe on this platform?
04-22-2023, 09:16 PM
#18
I get less than 10000 out of rears and have the same inside edge destroyed. Yes both left and right side. My rear brakes are also very worn at 30k. The fronts brakes are great. Base 991.2 so no ptv no track time and no awd. This wear pattern has been discussed in another thread. My tire dealer says nothing can be done and has replaced every tire under the 30k tread warranty. P zeros wear slightly different but same slope of wear On the rear. I've never seen the extreme edge worn like this on a P-zero. Yes uneven but not a big deal. I have run 33 psi fronts and they would go 50k I believe. The rears have run at 36 psi with this wear. At the most recent service Porsche set the pressures at 36/48. I'm going to run those pressures for the set going on now to see if higher pressue will give longer rear wear. The existing thread on this subject seemed to conclude the rear settings should not be changed and that excess wear is necessary for safety.
04-22-2023, 10:51 PM
#19
I get less than 10000 out of rears and have the same inside edge destroyed. Yes both left and right side. My rear brakes are also very worn at 30k. The fronts brakes are great. Base 991.2 so no ptv no track time and no awd. This wear pattern has been discussed in another thread. My tire dealer says nothing can be done and has replaced every tire under the 30k tread warranty. P zeros wear slightly different but same slope of wear On the rear. I've never seen the extreme edge worn like this on a P-zero. Yes uneven but not a big deal. I have run 33 psi fronts and they would go 50k I believe. The rears have run at 36 psi with this wear. At the most recent service Porsche set the pressures at 36/48. I'm going to run those pressures for the set going on now to see if higher pressue will give longer rear wear. The existing thread on this subject seemed to conclude the rear settings should not be changed and that excess wear is necessary for safety.
I switched to Cup 2 and the rears are almost done at 5000 miles, and the fronts have half life left (1 season and 2 track days). Tire wear is even across the tire and no evidence of inner tire wear on any of the tires. FWIW, my rear brakes went from 95% to 5% (in 1 track day) as I was much more comfortable and was quicker in the corners.
04-23-2023, 11:07 AM
#21
04-23-2023, 12:13 PM
#22
What my Cup2s look like when worn...
This was after 5 Track days plus several Mountain runs... many heat cycles
Your alignment is off...
Also if it was PTV causing it... the traction light on your dash would be going CRAZY
This was after 5 Track days plus several Mountain runs... many heat cycles
Your alignment is off...
Also if it was PTV causing it... the traction light on your dash would be going CRAZY
Last edited by snake eyes; 04-23-2023 at 12:14 PM.
04-23-2023, 12:56 PM
#23
Rennlist Member
Guys -- this is simple -- the toe setting is way, way off. Southbranch was spot on a number of posts ago with that and under-inflation. Also, have qualified shop also look for " worn" parts. (i.e. squatting)
04-23-2023, 01:08 PM
#24
Rennlist Member
I get less than 10000 out of rears and have the same inside edge destroyed. Yes both left and right side. My rear brakes are also very worn at 30k. The fronts brakes are great. Base 991.2 so no ptv no track time and no awd. This wear pattern has been discussed in another thread. My tire dealer says nothing can be done and has replaced every tire under the 30k tread warranty. P zeros wear slightly different but same slope of wear On the rear. I've never seen the extreme edge worn like this on a P-zero. Yes uneven but not a big deal. I have run 33 psi fronts and they would go 50k I believe. The rears have run at 36 psi with this wear. At the most recent service Porsche set the pressures at 36/48. I'm going to run those pressures for the set going on now to see if higher pressue will give longer rear wear. The existing thread on this subject seemed to conclude the rear settings should not be changed and that excess wear is necessary for safety.
Safety concerns are a bit silly for anyone advancing beyond the the novice level and for those who want to use their cars for more than just their daily commute. The factory settings are designed to promote understeer. This is in fact a 'safety decision' because Porsche and their lawyers believe that the average driver can better handle an understeer situation versus oversteer, especially in a rear engine car. This may be safer, but it is also slower. As we work to set-up our cars for track work, or even fun runs on the back roads, this understeer needs to be dialed out.
With factory components we have camber, toe, and pressures to work with. And perhaps tire size can be considered on the table as well. All need to be managed together to find the right balance in the car. In doing so there is a trade-off between tire wear and lap times. When we work with a customer we discuss the following: a) how often are you going to track the car b) what is your current experience level on track c) how does the car feel on track now? How does the front end feel? The back end? Can you break that down between entry, mid-corner, exit and braking? e) Which tracks will you be frequenting? d) What is your ideal trade-off between tire wear and lap time potential at the track? From this information, we work with the customer for the best set-up for them. Sometimes we get it right first time out of the box. Sometime we need to tweak after a little on track testing.
In general, we hate the PZero. The joke is the Zero stands for zero grip. But the worst part of the tire is that once they get to half life, the performance drops considerably and the noise level increases dramatically. We've also seen more issues with uneven wear and the tire chopping with the Pirelli versus other brands. The Michelin 4S is a MUCH better tire as a direct competitor.
36/48 tire pressure is MUCH too high for this car. The service tech who did that must be new and was following the door placard. That setting is the 'full load' spec that is designed for sustained speeds on the Autobahn over 160mph. The US spec is the comfort setting which is considerably lower. All this should be in the owner's manual. Running too high pressures causes a harsher ride and also reduces dry weather grip. You are effectively reducing the size of the tire foot print that touches the road when you are overinflated. Why reduce the handling capabilities of an incredible car in search of longer wearing tires? It seems like the wrong goal when driving a 911.
BTW, on track we are generally looking for even pressure across all 4 tires. With Michelin Sport Cup 2, that is in a range of 32-34. To achieve this cold pressures are about 25psi. Think about how crazy high Porsche set your pressures relative to a setting aimed at max grip and balanced handling!
@snake eyes Those Cup 2s look really great! We just put a set on our test mule along with the settings I posted earlier. Are you running stock suspension? Can you share your alignment set-up with us? What on-track hot tire pressures were you most happy at with this tire?
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04-23-2023, 03:23 PM
#25
Response to your quote from my quote
As both a tire dealer, a driver (I raced for nearly 15 years),and an instructor there is a lot here I don't agree with.
Safety concerns are a bit silly for anyone advancing beyond the the novice level and for those who want to use their cars for more than just their daily commute. The factory settings are designed to promote understeer. This is in fact a 'safety decision' because Porsche and their lawyers believe that the average driver can better handle an understeer situation versus oversteer, especially in a rear engine car. This may be safer, but it is also slower. As we work to set-up our cars for track work, or even fun runs on the back roads, this understeer needs to be dialed out.
With factory components we have camber, toe, and pressures to work with. And perhaps tire size can be considered on the table as well. All need to be managed together to find the right balance in the car. In doing so there is a trade-off between tire wear and lap times. When we work with a customer we discuss the following: a) how often are you going to track the car b) what is your current experience level on track c) how does the car feel on track now? How does the front end feel? The back end? Can you break that down between entry, mid-corner, exit and braking? e) Which tracks will you be frequenting? d) What is your ideal trade-off between tire wear and lap time potential at the track? From this information, we work with the customer for the best set-up for them. Sometimes we get it right first time out of the box. Sometime we need to tweak after a little on track testing.
In general, we hate the PZero. The joke is the Zero stands for zero grip. But the worst part of the tire is that once they get to half life, the performance drops considerably and the noise level increases dramatically. We've also seen more issues with uneven wear and the tire chopping with the Pirelli versus other brands. The Michelin 4S is a MUCH better tire as a direct competitor.
36/48 tire pressure is MUCH too high for this car. The service tech who did that must be new and was following the door placard. That setting is the 'full load' spec that is designed for sustained speeds on the Autobahn over 160mph. The US spec is the comfort setting which is considerably lower. All this should be in the owner's manual. Running too high pressures causes a harsher ride and also reduces dry weather grip. You are effectively reducing the size of the tire foot print that touches the road when you are overinflated. Why reduce the handling capabilities of an incredible car in search of longer wearing tires? It seems like the wrong goal when driving a 911.
BTW, on track we are generally looking for even pressure across all 4 tires. With Michelin Sport Cup 2, that is in a range of 32-34. To achieve this cold pressures are about 25psi. Think about how crazy high Porsche set your pressures relative to a setting aimed at max grip and balanced handling!
@snake eyes Those Cup 2s look really great! We just put a set on our test mule along with the settings I posted earlier. Are you running stock suspension? Can you share your alignment set-up with us? What on-track hot tire pressures were you most happy at with this tire?
Safety concerns are a bit silly for anyone advancing beyond the the novice level and for those who want to use their cars for more than just their daily commute. The factory settings are designed to promote understeer. This is in fact a 'safety decision' because Porsche and their lawyers believe that the average driver can better handle an understeer situation versus oversteer, especially in a rear engine car. This may be safer, but it is also slower. As we work to set-up our cars for track work, or even fun runs on the back roads, this understeer needs to be dialed out.
With factory components we have camber, toe, and pressures to work with. And perhaps tire size can be considered on the table as well. All need to be managed together to find the right balance in the car. In doing so there is a trade-off between tire wear and lap times. When we work with a customer we discuss the following: a) how often are you going to track the car b) what is your current experience level on track c) how does the car feel on track now? How does the front end feel? The back end? Can you break that down between entry, mid-corner, exit and braking? e) Which tracks will you be frequenting? d) What is your ideal trade-off between tire wear and lap time potential at the track? From this information, we work with the customer for the best set-up for them. Sometimes we get it right first time out of the box. Sometime we need to tweak after a little on track testing.
In general, we hate the PZero. The joke is the Zero stands for zero grip. But the worst part of the tire is that once they get to half life, the performance drops considerably and the noise level increases dramatically. We've also seen more issues with uneven wear and the tire chopping with the Pirelli versus other brands. The Michelin 4S is a MUCH better tire as a direct competitor.
36/48 tire pressure is MUCH too high for this car. The service tech who did that must be new and was following the door placard. That setting is the 'full load' spec that is designed for sustained speeds on the Autobahn over 160mph. The US spec is the comfort setting which is considerably lower. All this should be in the owner's manual. Running too high pressures causes a harsher ride and also reduces dry weather grip. You are effectively reducing the size of the tire foot print that touches the road when you are overinflated. Why reduce the handling capabilities of an incredible car in search of longer wearing tires? It seems like the wrong goal when driving a 911.
BTW, on track we are generally looking for even pressure across all 4 tires. With Michelin Sport Cup 2, that is in a range of 32-34. To achieve this cold pressures are about 25psi. Think about how crazy high Porsche set your pressures relative to a setting aimed at max grip and balanced handling!
@snake eyes Those Cup 2s look really great! We just put a set on our test mule along with the settings I posted earlier. Are you running stock suspension? Can you share your alignment set-up with us? What on-track hot tire pressures were you most happy at with this tire?
As for the pressure. That 36/48 has been consistently pumped into my tires by 3 different Porsche dealers in 3 different Porsche cars over the last 15 years at every single service by multiple techs. I have received lectures every time I go to the Porsche dealership about how dangerous running 33/36 is. I know it's bs. This time I though what the heck lets try 36/48. So far I can't tell a difference in handling. I just did 1000 miles and it made no difference in gas mileage either. I'm leaving it at those ballon settings to see if it keeps the rear from balding inside edges. I'll report back. Again all said was reference the rear only. As for the front. The wear is perfect and I never feel understeer unless I screw up or cause it intentionally. Intentionally as in breaking traction on purpose to know the current grip level. Something I do regularly on my 500 lb dirt bike with all nannies turned off before going triple digits offroad. Great way to read dirt. Now if I could get my 991 2 traction control to STAY off it would make me happy. Or maybe not.
04-23-2023, 03:48 PM
#26
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Love the discussion. . Really wish the clone thread about this could be merged. You asked of my alignment. The following is reference the rear only. It is in spec according to the tech at the Porsche dealer. Tech said he could change the rear camber to the edge of the green but the concensus from the clone thread is to leave it alone. For the driving I do the car feels perfect. I can saw constant curvy backroads with never a sound and have done so for 4 hours. My personal limit. I can't imagine another level of grip nor can I stand it.
As for the pressure. That 36/48 has been consistently pumped into my tires by 3 different Porsche dealers in 3 different Porsche cars over the last 15 years at every single service by multiple techs. I have received lectures every time I go to the Porsche dealership about how dangerous running 33/36 is. I know it's bs. This time I though what the heck lets try 36/48. So far I can't tell a difference in handling. I just did 1000 miles and it made no difference in gas mileage either. I'm leaving it at those ballon settings to see if it keeps the rear from balding inside edges. I'll report back. Again all said was reference the rear only. As for the front. The wear is perfect and I never feel understeer unless I screw up or cause it intentionally. Intentionally as in breaking traction on purpose to know the current grip level. Something I do regularly on my 500 lb dirt bike with all nannies turned off before going triple digits offroad. Great way to read dirt. Now if I could get my 991 2 traction control to STAY off it would make me happy. Or maybe not.
As for the pressure. That 36/48 has been consistently pumped into my tires by 3 different Porsche dealers in 3 different Porsche cars over the last 15 years at every single service by multiple techs. I have received lectures every time I go to the Porsche dealership about how dangerous running 33/36 is. I know it's bs. This time I though what the heck lets try 36/48. So far I can't tell a difference in handling. I just did 1000 miles and it made no difference in gas mileage either. I'm leaving it at those ballon settings to see if it keeps the rear from balding inside edges. I'll report back. Again all said was reference the rear only. As for the front. The wear is perfect and I never feel understeer unless I screw up or cause it intentionally. Intentionally as in breaking traction on purpose to know the current grip level. Something I do regularly on my 500 lb dirt bike with all nannies turned off before going triple digits offroad. Great way to read dirt. Now if I could get my 991 2 traction control to STAY off it would make me happy. Or maybe not.
04-23-2023, 04:33 PM
#27
I agree on the p zero lack of grip. Those tires needed to be hot before I could lean hard on them. Like smelling rubber burning hot.
04-23-2023, 04:49 PM
#28
I know I've tried advising them in the past but they still do it. I really like my last tech. He introduced himself before service. I don't know if it's a new thing but he took a video of the car on the lift and in the survey I was asked if a video was provided. He also met me at checkout to see if I had any concerns that needed to be addressed. I was provided with a Macsn loaner. The maintenance tech, customer service and the service director were all wonderful. I guess one of the reasons I'm at least trying that pressure is because the tech stated higher pressure might prevent the inner tire wear. I don't think pressure will make a difference because if you look at the rear of a 911 many have a tilt (camber) weighing the inside of the tires. This camber was also on some British sports cars of yore. It makes sense that under hard turns the outside tires are taking the weight and this camber allows a more flat footprint during high g manufacturing. It could be the inside wheel while turning is obviously less weighted but due to the negative camber drags the inside edge rapidly causing wear. Again the other thread brought me to the conclusion that this is just the price you pay for all this lovely grip. That dealer also gave me free merch out the door.
I agree on the p zero lack of grip. Those tires needed to be hot before I could lean hard on them. Like smelling rubber burning hot.
I agree on the p zero lack of grip. Those tires needed to be hot before I could lean hard on them. Like smelling rubber burning hot.
Being within spec still permits you to have toe out causing the inner edge wear.
You may find that the quality of the ride is a lot harsher at the higher pressures. First thing I did when picking up my car was dropping the air pressures to lower levels.
@jakermc Agree on the Cup 2 being happy in a narrow pressure range. I set out cold on them at 25F/27R and keep them at 33 F&R and they are very happy with even wear. Required letting out air every session. This is on a stock alignment, which I will change to an alignment more track oriented, but will also want to be able to dial in more negative camber.
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04-23-2023, 05:19 PM
#29
I would get the printed readout of your alignment.
Being within spec still permits you to have toe out causing the inner edge wear.
You may find that the quality of the ride is a lot harsher at the higher pressures. First thing I did when picking up my car was dropping the air pressures to lower levels.
@jakermc Agree on the Cup 2 being happy in a narrow pressure range. I set out cold on them at 25F/27R and keep them at 33 F&R and they are very happy with even wear. Required letting out air every session. This is on a stock alignment, which I will change to an alignment more track oriented, but will also want to be able to dial in more negative camber.
Being within spec still permits you to have toe out causing the inner edge wear.
You may find that the quality of the ride is a lot harsher at the higher pressures. First thing I did when picking up my car was dropping the air pressures to lower levels.
@jakermc Agree on the Cup 2 being happy in a narrow pressure range. I set out cold on them at 25F/27R and keep them at 33 F&R and they are very happy with even wear. Required letting out air every session. This is on a stock alignment, which I will change to an alignment more track oriented, but will also want to be able to dial in more negative camber.
04-24-2023, 10:12 AM
#30
As both a tire dealer, a driver (I raced for nearly 15 years),and an instructor there is a lot here I don't agree with.
Safety concerns are a bit silly for anyone advancing beyond the the novice level and for those who want to use their cars for more than just their daily commute. The factory settings are designed to promote understeer. This is in fact a 'safety decision' because Porsche and their lawyers believe that the average driver can better handle an understeer situation versus oversteer, especially in a rear engine car. This may be safer, but it is also slower. As we work to set-up our cars for track work, or even fun runs on the back roads, this understeer needs to be dialed out.
With factory components we have camber, toe, and pressures to work with. And perhaps tire size can be considered on the table as well. All need to be managed together to find the right balance in the car. In doing so there is a trade-off between tire wear and lap times. When we work with a customer we discuss the following: a) how often are you going to track the car b) what is your current experience level on track c) how does the car feel on track now? How does the front end feel? The back end? Can you break that down between entry, mid-corner, exit and braking? e) Which tracks will you be frequenting? d) What is your ideal trade-off between tire wear and lap time potential at the track? From this information, we work with the customer for the best set-up for them. Sometimes we get it right first time out of the box. Sometime we need to tweak after a little on track testing.
In general, we hate the PZero. The joke is the Zero stands for zero grip. But the worst part of the tire is that once they get to half life, the performance drops considerably and the noise level increases dramatically. We've also seen more issues with uneven wear and the tire chopping with the Pirelli versus other brands. The Michelin 4S is a MUCH better tire as a direct competitor.
36/48 tire pressure is MUCH too high for this car. The service tech who did that must be new and was following the door placard. That setting is the 'full load' spec that is designed for sustained speeds on the Autobahn over 160mph. The US spec is the comfort setting which is considerably lower. All this should be in the owner's manual. Running too high pressures causes a harsher ride and also reduces dry weather grip. You are effectively reducing the size of the tire foot print that touches the road when you are overinflated. Why reduce the handling capabilities of an incredible car in search of longer wearing tires? It seems like the wrong goal when driving a 911.
BTW, on track we are generally looking for even pressure across all 4 tires. With Michelin Sport Cup 2, that is in a range of 32-34. To achieve this cold pressures are about 25psi. Think about how crazy high Porsche set your pressures relative to a setting aimed at max grip and balanced handling!
@snake eyes Those Cup 2s look really great! We just put a set on our test mule along with the settings I posted earlier. Are you running stock suspension? Can you share your alignment set-up with us? What on-track hot tire pressures were you most happy at with this tire?
Safety concerns are a bit silly for anyone advancing beyond the the novice level and for those who want to use their cars for more than just their daily commute. The factory settings are designed to promote understeer. This is in fact a 'safety decision' because Porsche and their lawyers believe that the average driver can better handle an understeer situation versus oversteer, especially in a rear engine car. This may be safer, but it is also slower. As we work to set-up our cars for track work, or even fun runs on the back roads, this understeer needs to be dialed out.
With factory components we have camber, toe, and pressures to work with. And perhaps tire size can be considered on the table as well. All need to be managed together to find the right balance in the car. In doing so there is a trade-off between tire wear and lap times. When we work with a customer we discuss the following: a) how often are you going to track the car b) what is your current experience level on track c) how does the car feel on track now? How does the front end feel? The back end? Can you break that down between entry, mid-corner, exit and braking? e) Which tracks will you be frequenting? d) What is your ideal trade-off between tire wear and lap time potential at the track? From this information, we work with the customer for the best set-up for them. Sometimes we get it right first time out of the box. Sometime we need to tweak after a little on track testing.
In general, we hate the PZero. The joke is the Zero stands for zero grip. But the worst part of the tire is that once they get to half life, the performance drops considerably and the noise level increases dramatically. We've also seen more issues with uneven wear and the tire chopping with the Pirelli versus other brands. The Michelin 4S is a MUCH better tire as a direct competitor.
36/48 tire pressure is MUCH too high for this car. The service tech who did that must be new and was following the door placard. That setting is the 'full load' spec that is designed for sustained speeds on the Autobahn over 160mph. The US spec is the comfort setting which is considerably lower. All this should be in the owner's manual. Running too high pressures causes a harsher ride and also reduces dry weather grip. You are effectively reducing the size of the tire foot print that touches the road when you are overinflated. Why reduce the handling capabilities of an incredible car in search of longer wearing tires? It seems like the wrong goal when driving a 911.
BTW, on track we are generally looking for even pressure across all 4 tires. With Michelin Sport Cup 2, that is in a range of 32-34. To achieve this cold pressures are about 25psi. Think about how crazy high Porsche set your pressures relative to a setting aimed at max grip and balanced handling!
@snake eyes Those Cup 2s look really great! We just put a set on our test mule along with the settings I posted earlier. Are you running stock suspension? Can you share your alignment set-up with us? What on-track hot tire pressures were you most happy at with this tire?
I run cold 26 front and 28 rear per a 20 minute session at Road Atlanta (same exact specs as 991.1 GT3 guys). 32 front 34 rear "Hot a session, Cup 2's will fall off over 36PSI.. and than its just cool down laps, pits and bleed to get back inline.
I also prefer running "Ford Spec" Cup 2's not Porsche NO spec.
I'm a late braker/ trail braker, (style wise)... why I tear up pads..Running Pagid Yellows and Girodisc. (no power mods on the car).
Last edited by snake eyes; 04-24-2023 at 10:20 AM.