Tire chunking - thoughts
5/26/14, 08:16 AM
#1
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Tire chunking - thoughts
Got some tire chunking last time out at Limerock - not too deep, but I am a bit concerned for my next outing.
These tires (Sumitomo HTR Z III) are used only at the track, and they are a 300 treadwear rating. I purposely bought a harder tire with the intent of getting a lot of track days out of the set. The track I got the chunking at is brutal on front drivers side tires, so I'm not terribly surprised to see it chunked some. My next several planned outings are at venues that are less harsh on that front tire, so I'm not hugely concerned, but I'm interested if anyone has experience with chunking tires and how much it impacts the tire's strength.
Some pics:
These tires (Sumitomo HTR Z III) are used only at the track, and they are a 300 treadwear rating. I purposely bought a harder tire with the intent of getting a lot of track days out of the set. The track I got the chunking at is brutal on front drivers side tires, so I'm not terribly surprised to see it chunked some. My next several planned outings are at venues that are less harsh on that front tire, so I'm not hugely concerned, but I'm interested if anyone has experience with chunking tires and how much it impacts the tire's strength.
Some pics:
5/26/14, 08:19 AM
#2
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Oh - I did call tirerack to inquire about potential warranty. Sent pics, and they were quick to come back pointing to the blueish colored areas and how that indicates high temp conditions (racing...) and that these were therefore not warranty candidates. Oh well, had to try...
That said, I think the tire did get heated beyond it's max design temp, based on the chunking and the "greasy" feeling that developed towards the end of my sessions.
That said, I think the tire did get heated beyond it's max design temp, based on the chunking and the "greasy" feeling that developed towards the end of my sessions.
5/26/14, 08:39 AM
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Besides the tire temps, I don't think you have enough negative camber for the track in question. Stock camber settings are great for overall tire wear, not track conditions. The chunking actually looks like the tire was pinching under corner loading, and had no choice but to rip off.
Talk to the people more commonly running at that track to learn what tire and camber settings they use, they will have a good idea of what tires works best at the specific track.
Talk to the people more commonly running at that track to learn what tire and camber settings they use, they will have a good idea of what tires works best at the specific track.
5/26/14, 11:06 AM
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You may need more camber but these tires are kind of low end and have tall treads. Keep in mind the weight of the car also.
I ran full tread Kumho XS tires at a track day with no chunking but alot of bluish heat marks. The experienced guys at the track said it was most likely over driving and not enough camber.
I ran full tread Kumho XS tires at a track day with no chunking but alot of bluish heat marks. The experienced guys at the track said it was most likely over driving and not enough camber.
5/26/14, 12:19 PM
#6
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Besides the tire temps, I don't think you have enough negative camber for the track in question. Stock camber settings are great for overall tire wear, not track conditions. The chunking actually looks like the tire was pinching under corner loading, and had no choice but to rip off.
Talk to the people more commonly running at that track to learn what tire and camber settings they use, they will have a good idea of what tires works best at the specific track.
Talk to the people more commonly running at that track to learn what tire and camber settings they use, they will have a good idea of what tires works best at the specific track.
You may need more camber but these tires are kind of low end and have tall treads. Keep in mind the weight of the car also.
I ran full tread Kumho XS tires at a track day with no chunking but alot of bluish heat marks. The experienced guys at the track said it was most likely over driving and not enough camber.
I ran full tread Kumho XS tires at a track day with no chunking but alot of bluish heat marks. The experienced guys at the track said it was most likely over driving and not enough camber.
5/26/14, 04:20 PM
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That looks about right I think. You should have seen my stock Pirelli's after 4h of Gingerman. 
Lower tire pressure may help a bit, and more camber as others mentioned.
Lower tire pressure may help a bit, and more camber as others mentioned.
5/26/14, 05:23 PM
#8
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As I think back a bit, when I was at Jersey in April, I had the pressure set higher in all tires and I had no chunking at all... only a couple PSI... also, half way through the day at Limerock, I actually lowered the pressure from the early sessions (was like 42-43psi hot early in the day), and the chunking was not there at that point as I did quickly check the tires mid day.
Well, I'll have to wait to see how things go at Thompson next month.
And I think camber plates are in my near future. It's expensive to get fast on road courses
5/26/14, 08:35 PM
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Interestingly my stock Pirelli's held up great at Watkins Glen (2 days) and NYST which is extremely turny and technical - no chunking at all.
As I think back a bit, when I was at Jersey in April, I had the pressure set higher in all tires and I had no chunking at all... only a couple PSI... also, half way through the day at Limerock, I actually lowered the pressure from the early sessions (was like 42-43psi hot early in the day), and the chunking was not there at that point as I did quickly check the tires mid day.
Well, I'll have to wait to see how things go at Thompson next month.
And I think camber plates are in my near future. It's expensive to get fast on road courses
As I think back a bit, when I was at Jersey in April, I had the pressure set higher in all tires and I had no chunking at all... only a couple PSI... also, half way through the day at Limerock, I actually lowered the pressure from the early sessions (was like 42-43psi hot early in the day), and the chunking was not there at that point as I did quickly check the tires mid day.
Well, I'll have to wait to see how things go at Thompson next month.
And I think camber plates are in my near future. It's expensive to get fast on road courses
Interesting. I kept my Pirellis at 35psi prior to my fist session. They were ~44 after my first, and I haven't checked any more. I got a little chunking on my front left, but the rest had molten thread blocks.
Let us know how it goes after your next track day.
I'm a bit worried now. I'm about to sink some $$ into track day tires. This makes me think I should get harder compound at a lower price rather than getting better/stickier rubber.
And it won't help that by the time I get out to my next event I'll only have 1000 miles on the tires, so deep thread still.
5/26/14, 09:39 PM
#10
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The "better/stickier rubber" is a different compound and is designed specifically to operate properly at higher temps. That's why they're more expensive--when you get them hot, they work better than when they're cold--a heck of a lot better than lower tread-wear rated tires--and it takes a lot of heat to get these tires to operating temps. They shed, they don't chunk or melt. The high temp necessary for best traction is why they're not as safe on streets, as well; they don't get run on the street hard enough to get them to those temps, and as a result they aren't as predictable as more highly-treaded rubber.
Another note: the deeper the tread, the more flex there is to the blocks. That causes heat build-up and it's why the blocks can melt on some tires. Competition tires like the Nitto NT-01 and -05, or the Proxes 888s (there are plenty of others) have minimal tread for this purpose. You can also have them shaved even lower if you wish. Lastly, when you order high-performance tires, especially competition tires, you would be wise to heat-cycle them to have the compounds properly blended/bound in the tire itself. Just some thoughts.
Another note: the deeper the tread, the more flex there is to the blocks. That causes heat build-up and it's why the blocks can melt on some tires. Competition tires like the Nitto NT-01 and -05, or the Proxes 888s (there are plenty of others) have minimal tread for this purpose. You can also have them shaved even lower if you wish. Lastly, when you order high-performance tires, especially competition tires, you would be wise to heat-cycle them to have the compounds properly blended/bound in the tire itself. Just some thoughts.
Last edited by kcoTiger; 5/26/14 at 09:44 PM.
5/27/14, 02:44 AM
#11
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This is a very interesting thread. I'm enjoying the fact that some of us are more apt to try and go fast on a road course for minutes at a time rather than straight for seconds in our Mustangs.
5/27/14, 03:50 AM
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Is it possible that everyone is starting with too much tire pressure?
I was watching a YouTube video regarding the new Camaro Z/28, and there was a short section regarding the tire pressure and tire temperatures. They were recommending starting the tire pressures at 28psi, doing a warm up lap to bring the tires up to temperature, hopefully getting the tires up to 32-34psi, which should then be good for 2-3 laps, and then needing to allow the tires to cool down.
I was watching a YouTube video regarding the new Camaro Z/28, and there was a short section regarding the tire pressure and tire temperatures. They were recommending starting the tire pressures at 28psi, doing a warm up lap to bring the tires up to temperature, hopefully getting the tires up to 32-34psi, which should then be good for 2-3 laps, and then needing to allow the tires to cool down.
5/27/14, 06:13 AM
#13
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The "better/stickier rubber" is a different compound and is designed specifically to operate properly at higher temps. That's why they're more expensive--when you get them hot, they work better than when they're cold--a heck of a lot better than lower tread-wear rated tires--and it takes a lot of heat to get these tires to operating temps. They shed, they don't chunk or melt. The high temp necessary for best traction is why they're not as safe on streets, as well; they don't get run on the street hard enough to get them to those temps, and as a result they aren't as predictable as more highly-treaded rubber.
Another note: the deeper the tread, the more flex there is to the blocks. That causes heat build-up and it's why the blocks can melt on some tires. Competition tires like the Nitto NT-01 and -05, or the Proxes 888s (there are plenty of others) have minimal tread for this purpose. You can also have them shaved even lower if you wish. Lastly, when you order high-performance tires, especially competition tires, you would be wise to heat-cycle them to have the compounds properly blended/bound in the tire itself. Just some thoughts.
Another note: the deeper the tread, the more flex there is to the blocks. That causes heat build-up and it's why the blocks can melt on some tires. Competition tires like the Nitto NT-01 and -05, or the Proxes 888s (there are plenty of others) have minimal tread for this purpose. You can also have them shaved even lower if you wish. Lastly, when you order high-performance tires, especially competition tires, you would be wise to heat-cycle them to have the compounds properly blended/bound in the tire itself. Just some thoughts.
I may try splitting up my sessions a bit - 10 mins at speed, cooling lap and minute in the pits, then the rest of the session (another 10 mins). See if that helps prolong these tires.
Great feedback from the folks responding on this thread, appreciate the input
5/27/14, 06:16 AM
#14
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Thats why I ordered my car - best road course setup I could get in my price range! And 25 minute sessions on road courses >>>> 11 sec 1/4 mile pass in my opinion.
5/27/14, 07:30 AM
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The "better/stickier rubber" is a different compound and is designed specifically to operate properly at higher temps. That's why they're more expensive--when you get them hot, they work better than when they're cold--a heck of a lot better than lower tread-wear rated tires--and it takes a lot of heat to get these tires to operating temps. They shed, they don't chunk or melt. The high temp necessary for best traction is why they're not as safe on streets, as well; they don't get run on the street hard enough to get them to those temps, and as a result they aren't as predictable as more highly-treaded rubber.
Another note: the deeper the tread, the more flex there is to the blocks. That causes heat build-up and it's why the blocks can melt on some tires. Competition tires like the Nitto NT-01 and -05, or the Proxes 888s (there are plenty of others) have minimal tread for this purpose. You can also have them shaved even lower if you wish. Lastly, when you order high-performance tires, especially competition tires, you would be wise to heat-cycle them to have the compounds properly blended/bound in the tire itself. Just some thoughts.
Another note: the deeper the tread, the more flex there is to the blocks. That causes heat build-up and it's why the blocks can melt on some tires. Competition tires like the Nitto NT-01 and -05, or the Proxes 888s (there are plenty of others) have minimal tread for this purpose. You can also have them shaved even lower if you wish. Lastly, when you order high-performance tires, especially competition tires, you would be wise to heat-cycle them to have the compounds properly blended/bound in the tire itself. Just some thoughts.
I think the feedback I've seen here will steer me in the direction of going with softer compound. I'm still a bit worried because in the size I'm looking for, 275/40-19 there isn't that much to choose from. And even some of the more sticky compounds out there like Pilot SS or Bridgestone Potenza S-04 Pole position (which is my 1st choice right now) still have some chunking issues. I just read a post from S2000 forum where they were having the same issues. They were also overheating those tires.
Dmichaels also has a good point about taking a break in the middle of a session to cool off. I did 30min sessions on my stock Pirelli's and cried a little when I saw what that did to them.
5/27/14, 09:05 AM
#16
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Considered other sizes as well like 275/35/19 or 265/40/19? I like the staggered setup I have now (275 rear 255 front), but different sizes work too. To be honest tire selection options was a big part of why I went with 18" track setup. I would like 19's for the slightly larger overall diameter and low profile sidewall but there are tons of options for 18" wheels
If s2000's are getting chunking on a particular tire, I would definitely be concerned about it on the mustang with our significantly higher weight.
Also another option is take-off slicks... Several sites that have them and they are often quite cheap compared with new. I am considering that as an option as well. I think I could restrain myself from trying to find the grip limit on a set of slicks as they would corner much harder than my current tires and still be well within their capabilities.
If s2000's are getting chunking on a particular tire, I would definitely be concerned about it on the mustang with our significantly higher weight.
Also another option is take-off slicks... Several sites that have them and they are often quite cheap compared with new. I am considering that as an option as well. I think I could restrain myself from trying to find the grip limit on a set of slicks as they would corner much harder than my current tires and still be well within their capabilities.
5/27/14, 10:34 AM
#17
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My current tires are 888's front and back, and when they are treadless I'll use them on track days until they're worn out. If you can find some used slicks that are in good shape, it will keep your regular tires from being chewed up so much. Of course, you then have to find a set of wheels to use the slicks with...
5/27/14, 10:40 AM
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I ran 1 set of Nitto NT01's on my Evo for 6 and a half years. Believe it or not they where still effective at 6 years old. Set my fastest lap times at streets of willow here in socal. I got about 7 track days out of them over that time.
Very good tires with the right camber and tire pressure. On a 5.0, I would start at 30 psi front and rear to start. When new break them in gradually as they heat up quick at full tread depth. I started at 34 psi only to be at 48 psi at the end of a session!
Also a wider tire will last longer. More contact patch to distribute the weight.
Very good tires with the right camber and tire pressure. On a 5.0, I would start at 30 psi front and rear to start. When new break them in gradually as they heat up quick at full tread depth. I started at 34 psi only to be at 48 psi at the end of a session!
Also a wider tire will last longer. More contact patch to distribute the weight.
5/28/14, 01:09 PM
#20
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Indeed you are correct. I share the same opinion. I hope to make it to the Nurburgring this year at least one time. Next year I'm shooting for at least 20 laps.