HOW TO: Read tire wear
07-21-2014, 09:41 AM
#1
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HOW TO: Read tire wear
So after 19,000 glorious miles with my PCS, and their PZero's, I think it is time for a change. Problem is in not sure and have no clue.
?1. How do you know when your tread wear has worn to a point that it needs replaced.
?2. Should you always do 4 wheel replacement or is doing 2 rear then the 2 front ok?
?3. During AX events I people say to me "you rolled your sidewalls" and express it in a way that makes it sound like a good thing. What does this mean?
?4. What effect does tire pressure have and what should it be for AX and or track days.
Thanks in advance for any advice.
?1. How do you know when your tread wear has worn to a point that it needs replaced.
?2. Should you always do 4 wheel replacement or is doing 2 rear then the 2 front ok?
?3. During AX events I people say to me "you rolled your sidewalls" and express it in a way that makes it sound like a good thing. What does this mean?
?4. What effect does tire pressure have and what should it be for AX and or track days.
Thanks in advance for any advice.
Last edited by uhear; 07-21-2014 at 03:43 PM.
07-21-2014, 11:20 AM
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I replace tires on matched pairs of 2 when below the wear bars of if I let them go too far and get cording.
I log tire wear on every oil change receipt. I use a simple tire gauge. I take 4 measurement of each tire. 1 inner. 2 middle. 1 outer.
New tires are 9 and 10/32's. I've gone as low as 1's and 2's. I don't drive in the rain. YMMV.
I log tire wear on every oil change receipt. I use a simple tire gauge. I take 4 measurement of each tire. 1 inner. 2 middle. 1 outer.
New tires are 9 and 10/32's. I've gone as low as 1's and 2's. I don't drive in the rain. YMMV.
07-21-2014, 12:53 PM
#3
Burning Brakes
I haven't tracked or AX'ed my car, but got an amazing 19K miles on my first rear set of OEM 19" Goodyear F1's, fronts still good. Shortly thereafter I had a sidewall failure and had to replace one of those. Now at almost 35K miles, I am guessing I will replace all four around 40K. That's all pretty reasonable for summer performance tires.
07-21-2014, 03:42 PM
#4
Tire wear is the most variable things we deal with in a performance car.
I've gotten as much as 20K on all 4 tires on a 997.1. They were Bridgestone RE050's. I've gotten as little as 3500 miles on all 4 PS2 tires that came on my 997.2 GTS. All 4 tires were showing cords on the outside of the tires when they were replaced.
The reason, obviously, is how the car is used. I had 5 track days and 1 AX day on the tires that died so quickly. The car itself was only 3500 miles old (a little over 3 months) and also needed front pads at the same time.
But I have to say, I've never heard of anyone getting 40K miles from all 4 tires on a 911 !! The usual rule of thumb is that you can get twice as many miles from the front tires as from the rears.
40K on a set of rears? Amazing. That car must be driven very gently indeed.
To answer specific questions:
1. Replace tires when you're down to the wear bars. Often the wear will not be even across the tire, so replace tires when any part of the tread is down to the bars.
2. Given the fact that the typical wear is much heavier on the rear, I've replaced just 2 tires on multiple occasions, where the tires not being replaced still have at least 50% tread. If they were lower than that, in an abundance of caution I'd replace all 4.
3. "Rolling the sidewalls" means that you're generating enough cornering force that as the car leans in a turn, the outside tires are leaning up against their sidewall, causing the very outside edge of the tire to wear. It shows that you're driving aggressively, BUT the car isn't using its tires effectively when that happens. The usual cure is to adjust your alignment to have more negative camber. The downside is that the negative camber will make your tires last longer and work better on the track or AX course; and they will wear faster (on the inside edges) the rest of the time. Everything is a compromise.
4. Reduced to the bare essentials, tire pressure keeps your rims from hitting the ground. There is a recommended tire pressure from Porsche. In fact, there are multiples. Full load/high speeds; light load/high speeds; and "comfort."
For autocross, as a starting point, I'd recommend you use the "comfort" settings when the car is cold. As you're driving the tire pressures will increase, often dramatically. I've seen my go up 10-12 psi on the track. Generally speaking, most drivers in stock cars try to keep their pressures from going much over 40 psi, which often means that you're letting air out over the course of the day. That means that you need to put that air back in to drive home afterwards. If pressure get too high the tires feel "greasy" and you start sliding around more. But tire pressure, which of course relates to tire temperature, is a very complicated subject and if you check I'm sure you'll find countless threads that address the issue in much greater detail.
I hope that helps.
DMoore
'13 991S
'13 Panamera GTS
I've gotten as much as 20K on all 4 tires on a 997.1. They were Bridgestone RE050's. I've gotten as little as 3500 miles on all 4 PS2 tires that came on my 997.2 GTS. All 4 tires were showing cords on the outside of the tires when they were replaced.
The reason, obviously, is how the car is used. I had 5 track days and 1 AX day on the tires that died so quickly. The car itself was only 3500 miles old (a little over 3 months) and also needed front pads at the same time.
But I have to say, I've never heard of anyone getting 40K miles from all 4 tires on a 911 !! The usual rule of thumb is that you can get twice as many miles from the front tires as from the rears.
40K on a set of rears? Amazing. That car must be driven very gently indeed.
To answer specific questions:
1. Replace tires when you're down to the wear bars. Often the wear will not be even across the tire, so replace tires when any part of the tread is down to the bars.
2. Given the fact that the typical wear is much heavier on the rear, I've replaced just 2 tires on multiple occasions, where the tires not being replaced still have at least 50% tread. If they were lower than that, in an abundance of caution I'd replace all 4.
3. "Rolling the sidewalls" means that you're generating enough cornering force that as the car leans in a turn, the outside tires are leaning up against their sidewall, causing the very outside edge of the tire to wear. It shows that you're driving aggressively, BUT the car isn't using its tires effectively when that happens. The usual cure is to adjust your alignment to have more negative camber. The downside is that the negative camber will make your tires last longer and work better on the track or AX course; and they will wear faster (on the inside edges) the rest of the time. Everything is a compromise.
4. Reduced to the bare essentials, tire pressure keeps your rims from hitting the ground. There is a recommended tire pressure from Porsche. In fact, there are multiples. Full load/high speeds; light load/high speeds; and "comfort."
For autocross, as a starting point, I'd recommend you use the "comfort" settings when the car is cold. As you're driving the tire pressures will increase, often dramatically. I've seen my go up 10-12 psi on the track. Generally speaking, most drivers in stock cars try to keep their pressures from going much over 40 psi, which often means that you're letting air out over the course of the day. That means that you need to put that air back in to drive home afterwards. If pressure get too high the tires feel "greasy" and you start sliding around more. But tire pressure, which of course relates to tire temperature, is a very complicated subject and if you check I'm sure you'll find countless threads that address the issue in much greater detail.
I hope that helps.
DMoore
'13 991S
'13 Panamera GTS
Last edited by DMoore; 07-22-2014 at 04:47 AM.
07-21-2014, 03:58 PM
#5
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As a starting point, make sure your tyres are always inflated to the manufacturers recommended pressures, and during track events monitor pressures to ensure that heat does not result in significant over inflation...
07-21-2014, 04:12 PM
#7
Rennlist Member
Tire wear is the most variable things we deal with in a performance car.
I've gotten as much as 20K on all 4 tires on a 997.1. They were Bridgestone RE050's. I've gotten as little as 3500 miles on all 4 tires on my 997.2 GTS. All 4 tires were showing cords on the outside of the tires when they were replaced.
I've gotten as much as 20K on all 4 tires on a 997.1. They were Bridgestone RE050's. I've gotten as little as 3500 miles on all 4 tires on my 997.2 GTS. All 4 tires were showing cords on the outside of the tires when they were replaced.
The reason, obviously, is how the car is used. I had 5 track days and 1 AX day on the miles that died so quickly. The car itself was only 3500 miles old (a little over 3 months) and also needed front pads at the same time.
But I have to say, I've never heard of anyone getting 40K miles from all 4 tires on a 911 !! The usual rule of thumb is that you can get twice as many miles from the front tires as from the rears.
40K on a set of rears? Amazing. That car must be driven very gently indeed.
To answer specific questions:
1. Replace tires when you're down to the wear bars. Often the wear will not be even across the tire, so replace tires when any part of the tread is down to the bars.
2. Given the fact that the typical wear pattern is much heavier on the rear, I've replaced just 2 tires on multiple occasions, where the tires not being replaced still have at least 50% tread. If they were lower than that, in an abundance of caution I'd replace all 4.
3. "Rolling the sidewalls" means that you're generating enough cornering force that as the car leans in a turn, the outside tires are leaning up against their sidewall, causing the very outside edge of the tire to wear. It shows that you're driving aggressively, BUT the car isn't using its tires effectively when that happens. The usual cure is to adjust your alignment to have more negative camber. The downside is that the negative camber will make your tires last longer and work better on the track or AX course; and they will wear faster (on the inside edges) the rest of the time. Everything is a compromise.
But I have to say, I've never heard of anyone getting 40K miles from all 4 tires on a 911 !! The usual rule of thumb is that you can get twice as many miles from the front tires as from the rears.
40K on a set of rears? Amazing. That car must be driven very gently indeed.
To answer specific questions:
1. Replace tires when you're down to the wear bars. Often the wear will not be even across the tire, so replace tires when any part of the tread is down to the bars.
2. Given the fact that the typical wear pattern is much heavier on the rear, I've replaced just 2 tires on multiple occasions, where the tires not being replaced still have at least 50% tread. If they were lower than that, in an abundance of caution I'd replace all 4.
3. "Rolling the sidewalls" means that you're generating enough cornering force that as the car leans in a turn, the outside tires are leaning up against their sidewall, causing the very outside edge of the tire to wear. It shows that you're driving aggressively, BUT the car isn't using its tires effectively when that happens. The usual cure is to adjust your alignment to have more negative camber. The downside is that the negative camber will make your tires last longer and work better on the track or AX course; and they will wear faster (on the inside edges) the rest of the time. Everything is a compromise.
4. Reduced to the bare essentials, tire pressure keeps your rims from hitting the ground. There is a recommended tire pressure from Porsche. In fact, there are multiples. Full load/high speeds; light load/high speeds; and "comfort."
For autocross, as a starting point, I'd recommend you use the "comfort" settings when the car is cold. As you're driving the tire pressures will increase, often dramatically. I've seen my go up 10-12 psi on the track. Generally speaking, most drivers in stock cars try to keep their pressures from going much over 40 psi, which often means that you're letting air out over the course of the day. That means that you need to put that air back in to drive home afterwards. If pressure get too high the tires feel "greasy" and you start sliding around more. But tire pressure, which of course relates to tire temperature, is a very complicated subject and if you check I'm sure you'll find countless threads that address the issue in much greater detail.
I hope that helps.
DMoore
'13 991S
'13 Panamera GTS
For autocross, as a starting point, I'd recommend you use the "comfort" settings when the car is cold. As you're driving the tire pressures will increase, often dramatically. I've seen my go up 10-12 psi on the track. Generally speaking, most drivers in stock cars try to keep their pressures from going much over 40 psi, which often means that you're letting air out over the course of the day. That means that you need to put that air back in to drive home afterwards. If pressure get too high the tires feel "greasy" and you start sliding around more. But tire pressure, which of course relates to tire temperature, is a very complicated subject and if you check I'm sure you'll find countless threads that address the issue in much greater detail.
I hope that helps.
DMoore
'13 991S
'13 Panamera GTS
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07-21-2014, 04:21 PM
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You guys are the BEST. This forum is an awesome resource!
Ok, so here is my dilemma now.
I checked the wear bars, excellent to know how to use these, and I would estimate the Fronts as being solidly OK - at least 50% wear left in them. However, the Rears are pretty much ready for replacement now or in the next month. I would like to transition to Michelin PSS but I am not ready to replace the Fronts.
Is is sacrilegious to continue to run the Pzero's on the front and buy new M-PSS for the rear?
On another note, the wear throughout the width of all the tires were very even. A little more wear on the inside of both the rears but not too bad at all.
Ok, so here is my dilemma now.
I checked the wear bars, excellent to know how to use these, and I would estimate the Fronts as being solidly OK - at least 50% wear left in them. However, the Rears are pretty much ready for replacement now or in the next month. I would like to transition to Michelin PSS but I am not ready to replace the Fronts.
Is is sacrilegious to continue to run the Pzero's on the front and buy new M-PSS for the rear?
On another note, the wear throughout the width of all the tires were very even. A little more wear on the inside of both the rears but not too bad at all.
07-21-2014, 04:25 PM
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Don't mix tire brands nor type.
Then in 20,000 more miles, make the switch to MSS.
Do you have PDCC??
Then in 20,000 more miles, make the switch to MSS.
Do you have PDCC??
No clue what this is - Do you have PDCC??
07-21-2014, 04:29 PM
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07-21-2014, 05:42 PM
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[QUOTE=Larry Cable;11521950]have you had an alignment, how much -ve camber are you running?
+1 very important to ensure that your car is properly aligned for any driving situation, especially the track!
At that point the car was still running with the factory alignment settings. When I replaced that first set of tires I maxed out the front negative camber (-1.2 degrees IIRC) and set the rears at about -1.0. It didn't completely solve the problem (only GT3 LCA's and -2.0 or more would have) but it certainly helped.
But as I pointed out, the tradeoff was much faster street wear. Not that much of an issue for me, since I was doing enough track/AX driving that the tires only lasted 4-5 track days before needing replacement.
DMoore
'13 991S
'13 Panamera GTS
+1 very important to ensure that your car is properly aligned for any driving situation, especially the track!
At that point the car was still running with the factory alignment settings. When I replaced that first set of tires I maxed out the front negative camber (-1.2 degrees IIRC) and set the rears at about -1.0. It didn't completely solve the problem (only GT3 LCA's and -2.0 or more would have) but it certainly helped.
But as I pointed out, the tradeoff was much faster street wear. Not that much of an issue for me, since I was doing enough track/AX driving that the tires only lasted 4-5 track days before needing replacement.
DMoore
'13 991S
'13 Panamera GTS
07-21-2014, 06:16 PM
#13
Rennlist Member
You guys are the BEST. This forum is an awesome resource!
Ok, so here is my dilemma now.
I checked the wear bars, excellent to know how to use these, and I would estimate the Fronts as being solidly OK - at least 50% wear left in them. However, the Rears are pretty much ready for replacement now or in the next month. I would like to transition to Michelin PSS but I am not ready to replace the Fronts.
Is is sacrilegious to continue to run the Pzero's on the front and buy new M-PSS for the rear?
On another note, the wear throughout the width of all the tires were very even. A little more wear on the inside of both the rears but not too bad at all.
Ok, so here is my dilemma now.
I checked the wear bars, excellent to know how to use these, and I would estimate the Fronts as being solidly OK - at least 50% wear left in them. However, the Rears are pretty much ready for replacement now or in the next month. I would like to transition to Michelin PSS but I am not ready to replace the Fronts.
Is is sacrilegious to continue to run the Pzero's on the front and buy new M-PSS for the rear?
On another note, the wear throughout the width of all the tires were very even. A little more wear on the inside of both the rears but not too bad at all.
07-21-2014, 06:18 PM
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07-21-2014, 06:25 PM
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