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It's heating-cooling cycle for tires. Before you go on the track, the tires are cool. When you're riding they heat up and after you're done they cool down again.

Exactly what happens I don't know, but race tires are made of a mixture of different compounds, the physical properties of which change as the tires warm up and cool down. To avoid premature wear, it's advisable to keep them at the operating temperature between riding sessions.
 

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Discussion Starter #3
Im running a race take off right now and from what ive heard, this is dangerous because it could slide out?
 

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Im running a race take off right now and from what ive heard, this is dangerous because it could slide out?
Yes, it's not good to run race tires on the street. Primarily because they are designed to grip at a certain temperature. A temperature that you can not get to on the street and certainly can not maintain.

Also, race rubber has limited heat cycles. As EZ mentioned above, it's the heat up and cool down of the rubber. Race rubber is designed without the preservatives and additives that keep the tire oils from permeating out of the rubber. A race tire is built to withstand about 8-10 heat cycles. After that, is basically shot, regardless of the amount of rubber still on it. It just gets too hard and will not grip any longer. That's why you see racers using tire warmers. They get the rubber up to temp and keep in there so it has minimum heat cycles.

You're risking a lot running a race take-off on the street.
 

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El Zilcho is correct. The heat cycle is the time between when your tires heat up and cool down. During the manufacturing process the rubber is CURED at a specific temperature depending on the type of rubber the curing is what makes it malleable or harder. No matter the compound the enemy of rubber is heat, especially during heating and then cooling cycle this makes the oils and other compounds come to the surface also known as seeping. Tires that have repeatedly gone through this process will have a bluish tint on the edges. This happens also regardless of riding them or not rubber has an effective shelf life once tires are produced they continue to cure I.e making the compounded harder and harder from reaction with the air and ambient temperature. How long that shelf life is depends on the type of rubber compound. There are some rubber compounds called cleaner stock that due to their chemical composition pretty much makes them immune to the curing process but unfortunately this compound cant be used to make tires as it wont hold form. I used to work in the rubber industry manufacturing tires and vehicle rubber sealing systems.
 

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Discussion Starter #6
thanks for all the responses, i have noticed it not as grippy as it was at first, seems to want to slide in the corners
 

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Race tires aren't good for the street because they are meant to be operated at a higher temperature. They don't stick very well when they're cold and street speeds do not put enough heat into them. They should also be used with tire warmers.

But as for heat cycles, here is a quote from Dunlop Racing:
"Heat Cycles is not an issue with Dunlop racing tires. The more important factor is how much tread is left on the tire. Stable fact: thicker rubber has more grip and develops more heat, thinner rubber has less grip and runs cooler. After each session you have less grip. As the tire wears out, you have less and less grip. It could be slight or it could be large.

Some riders call it heat cycling, but, in actuality, its the rubber getting thinner and thinner. It truly depends on how much the tire is worn out, and your specific demands for grip that determines when the tire is not usable for you."
 

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since when is a heat cycle not an issue.
dunlop are not imune to the heat cycle.
and as for 8 to 10 heat cycles in a set of tyres that would be a exception rather than the rule.
from memery the new R10's and the S20's are designed for higher heat cycles dew to those tyres being made for the track day heros and the R10 a control tyre for some classes of raceing.
4 or 5 is more it. a race tyre is normaly shot after a days racing. a track day tyre maybe 3 to 4 track days.
as said above a race tyre isn't going to get hot on the street unless you pushing really hard OR running it real soft.
in which case you might as well run 50 psi for all the grip your going to get from a cold race tyre on the street.
i dought a street tyre is affected by heat cycles mainly because they don't get that hot riding on the street. you may think they do but in reality they not getting to the 85-86 deg C that is the sweet temp according to some experts as the ideal temp for maximum grip for a race tyre.
i'm a sceptic of the BS some tyre companies put out.
look at the reconmended tyre pressures where do they get that shit, way the fuk out.
my 2012 zx10 has recomended 36F 42R cold on the stock rubber,, pressures are higher for replacement rubber.
thats fine if you are into drifting i weight 75KG's and 30F and 30R solo is good grip and feel well thats what i get anyway. and 34F 36R 2 up from stock BT016's. 003's are more like the 2 up pressures of the 016's because their softer & stickier
 

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Proof is in the results. I have run a tire , set it in my shop for a year then put it on a long street ride (150+ miles) then took it out to the local club event a week later and won a 20 lap race setting a "faster than most can can do" pace. Use discretion and feel them out. We all know where we stand in this game and if you want to push your personal limits don't do it on aged rubber...unless you're broke...but stay clear of those that spent the money on the good rubber because they don't want you crashing into them...btw they were Michelin Slicks
 

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Back in the day the "heat cycle" used to be a concern for DOT race tires, but Dunlop now says heat-cycling is not a problem with the Q3, for example. It is a matter of the rubber getting thinner which is a natural wear characteristic. Tire warmers won't affect this. Again, this is from Dunlop directly:

Heat Cycles is not an issue with Dunlop racing tires as it would be with other brands. The more important factor is how much tread is left on the tire. Stable fact: thicker rubber has more grip and develops more heat, thinner rubber has less grip and runs cooler. After each session you have less grip. As the tire wears out, you have less and less grip. It could be slight or it could be large.

Some riders call it heat cycling, but, in actuality, its the rubber getting thinner and thinner. It truly depends on how much the tire is worn out, and your specific demands for grip that determines when the tire is not usable for you.
 

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As many have mentioned a heat cycle is taking a tire up to operating temp and then letting it cool down. Different TYPES of tires have different requirements. As a tire goes through a heat cycle, oils from the tire carcass are released (the bluing you see on the surface of the tire). Why do we care? As these oils are released the tire starts to get hard and loses grip performance. If you take a brand new tire and put your thumb nail in it, the tire will mark and then absorb the mark making it disappear. On a old tire the nail mark wont go away because the tire is too hard. Here are the big differences between race and street tires.

DOT/Slicks - DOT/Slicks are designed for one thing, to have maximum amount of grip possible. A disadvantage to having max grip is the loss of longevity. As the the tire goes through a heat cycle, the tire loses a huge amount of grip available to the rider. Every manufacture is different but we have seen tires last a single heat cycle and then dumped because there was no grip left, even though there was plenty of rubber. So to help combat this we use tire warmers. By using tire warmers we make the heat cycle one long continuous one throughout the day. The key thing to remember is a heat cycle time length is not important, it's the temp fluctuation that kills the grip. So if a race tire generally gets 4 heat cycles, and you use tire warmers throughout 1 day of riding keeping the temp constant, that is considered 1 heat cycle.

Street Tires Street tires work a little differently. The goal is to get longevity, at the sacrifice of grip (compared to DOT/Slicks). They do this by running higher silica content and changing the rubber formula. By doing this, the tire can go through numerous heat cycles without the compromise of grip. Now when the tire goes through a heat cycle the grip level only drops very little and you can focus more on the amount of tire you have left. Keep in mind that street tires will still blue like race rubber, BUT the drop in grip performance is not the same. In the past I have run Q2s on the track and the fronts ALWAYS were blue, but I never had a drop in grip performance like I currently do on DOTs.
 
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