DUNLOP-RTS

Heat Cycles

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Steve: Great information in all of your posts! I have a question that is related to tire warmers and heat cycles.

 

I'm currently an intermediate rider who has been using Q2s. I don't currently own a tire warmer. I've thought of jumping up to the D211GPA tires.

 

If I go with the D211GPA tires, will I need tire warmers? In another post, you indicated that the tire warmers just get your tires warmed up so they are ready to go in your first couple of laps without having to heat them in the first couple of laps. However, I have heard and read that when running "race" tires, to include "DOT race," that you need tire warmers also to reduce the number of heat cycles through the tire. As I understand, this is necessary because race tires, unlike the road/track tires, are not manufactured to go through multiple heat cycles. Is there any truth to this?

 

Ultimately, what I'm trying to figure out is how important would tire warmers be if I switch from the Q2s to the D211GPA? Without a tire warmer, I have not had any problems gradually warming up my Q2s in the first couple of laps each session, so I'm wondering if I would be able to do the same with D211GPAs while maintaining good longevity for the tires and getting them up to the correct temp.

 

Thanks!

 

Art

 

Art,

 

Yes, tire warmers put heat into the tire, so you don't have to on the first couple of laps. Other than that there is nothing magical about them. They don't change the rubber compound from bad to good.

 

Now lets tackle the issue of HEAT CYCLES.

 

 

Heat cycling of the tire is a very confusing and misunderstood area. I will say that I have heard that other brands are well known for "going off" or "heat cycling" and I will leave that conversation to another thread another day.

 

For now I'm going to stick with Dunlop's, as that is what I know.

 

Do tires heat cycle? Yes

 

Is this the most important factor in tires? NO! in fact it is not very significant, and very over emphasized.

 

Certainly making a tire go from 250 deg to negative 10 deg over and over is not the best thing you can do to a tire, but consider that placing it on a warmer, at 190 deg, for 8 hours is not any better. Both extremes are not the best for the tire.

 

We all hear about "Heat Cycle", but almost never do we hear talk about the thickness of the tire, or tread depth/wear. Fact: The thicker the tread rubber, the more grip. The thinner the tread rubber, the less grip. So as you ride on the tire, session after session, the rubber is getting thinner and there is less and less grip. Often this is mistaken for "heat cycle", and the rider now places his attention on his warmers and not on the real important factor of how much tread rubber is left on his tire.

 

Odd rituals start to crop up regarding tire warmers: Riders come back to the pits and RUSH to put their warmers on and crank them up to full, all in an attempt to "stop the heat cycle!". When buying used tires, riders rate the tire by how many heat cycles it has, not the tread depth.

 

It is a mistake to emphasize heat cycling over tread depth, with Dunlops.

 

So lets get real, which tire would you want to buy:

 

1) A tire with 10 laps and never had warmers?

2) A tire with 8 sessions and was on the warmers all day (8 hours) and never cooled down?

3) A new tire that was on a warmer for 8 hours only and never used?

 

I personally would pick #3 because it has the thickest tread, and #1 would be my second pick because it has less laps and probably more tread than #2. Notice how the heat cycles does not play into my personal choice in this matter, but the tread thickness does.

 

You can use a D211GPA or any other Dunlop tire without warmers and have no problems. ( Make sure you do heat the tire up for the first couple laps before you get with it.)

 

You might have a very small decrease in grip or life, but that would be very small and most likely not noticeable over the 1-5 track days you will get out of the tires. You would be spliting hairs on the performance level and tire life with/without warmers. Even if you were to do back to back tests, you would find that if in just 1 session in the life of the tire, you went 5 seconds faster, that would make more of a difference than heat cycling because you used more tread rubber in that session.

 

Heat cycles are not a total myth, but they do not make as big a difference as the internet would lead you to believe.

 

Tire warmers are good thing to have if you want to get going right out of the pits. They are not a requirement. Note that our recommendation for track day warmers has you putting the warmers on after a session and not plugging them in right away. This is so you don't needlessly force heat into the tire continuously for no reason. http://www.dunloprac...com/Warmers.pdf

 

Ever notice that the chatter about heat cycles started about the time tire warmers became cheaper and more readily available? Do you think there could be an urban legend that started because of this increased supply?

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Now that's a very, very interesting thread indeed, so thank you so very much for sharing it. It definitely explains the reason why I feel tires are going off, when in fact it's mainly wear that's the bigger factor.

 

This is going to be part of my racing/trackday book of setup.

 

Bullet

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Are 209 GPA's that have a manufacture date of 07, have had about 9 laps on them, but have been in freezing temperatures still reliable track use tires?

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Are 209 GPA's that have a manufacture date of 07, have had about 9 laps on them, but have been in freezing temperatures still reliable track use tires?

 

2007 technology. OK to use, if you are cool with that technology version.

 

That was the tire before the D209GPA Spec AMA tire.

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Hi All,

 

Just had another recent conversation with our Dunlop man Steve on this subject, as it has come up at the School. We saw some tires that were quite worn, but yet from a quick look did not appear to be so. They had rubber near the edge, and in the middle, but had been worn quite a bit between. This was really made clear when we just cut the tire to see the wear. As mentioned a quick look at the tire didn't show how worn it was.

 

I'm going to recommend if you get a chance with a used tire, cut it and have a look. This can be quite educational, certainly was for some of us at the School to cut the tire (not the bead) and see what depth of material is there.

 

Best,

CF

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Answer Man,

The tread depth appears quite deep on my new Q3+ tires that I am using for street riding.  I also purchased a set of N-Tec slicks for use on the track for honing my skills. Question: Is the traction of the slicks better than the updated technology of the new  Q3+ ?  Trying to decide what to take to my scheduled CSS in June.   Should I put on the new slicks or ride the 400 mile Q3+?

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Certainly the race tire will have more grip and be better for the track.

Using a 400 mile worn street tire is not a good option for the track.

I would use the Race Tire on the track and then go back to your street Q3 for the street.

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@DUNLOP-RTS If using a "street tire" at the track, how new should you want the tire before bringing it to a trackday or school? From your answer above I'm assuming that some use is okay but 400 miles is too much. Clarifying question: What mileage is good to assume the mold release agent has been scrubbed from the tires and they're ready for track use?

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On the topic of thinner tread having less grip - isn't it the same rubber compound all the way through the tyre? Or do you mean less overall grip/less grip remaining? 

 

Jaybird - can only speak from my experience, but knowing how much tyre I use on a day I wouldn't start a day unless I have enough tread to get me through. In saying that I have once gone right past the tread wear marker and worn the tread sipes right down on the side and didn't notice it ride any differently...

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@mugget Interesting observations. Makes me wonder: what really causes a tire to lose grip. Race announcers are always talking about it, especially in MotoGP. When they show the bikes in Parc Ferme, I don't see worn tires.

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Excellent questions as I too have seen advanced riders and racers at track days hit the track with no slicks tread indicators remaining. While I try to limit my slicks to a maximum of two track days, I worked with a track day safety rider on some turning points that was on his 11th track day on the same set of slicks.  He said they were like wet tires until they warmed up but after that they ran at about 75% grip.  I would have assumed they would have dropped off to 5%.

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When tire is very worn and the rubber is thin it is much harder to heat up the tire and keep it warm, that is the biggest thing I notice on a very worn race tire, or in some cases the tire profile is changed through wear which can change handling. 

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I'll also add that I'm not sure about other brands, but I have ridden on some Dunlop slicks that had cords starting to show through on the rear tire and they still had good grip. I was only running a medium pace but they felt fine. It's certainly not something I'd recommend doing and I'd not do it on my own bike, ever, but it seems like as long as there is rubber left - even if thin - there is still some grip, as long as the tire is able to get, and stay, warm enough. I'm not sure whether that would be true for other brands or for street tires, and when you factor in actual AGE that is a different conversation, since the rubber can get dried out over time and lose grip.

In regards to profiling, I rode on someone else's worn front tire and the profile had changed enough that I felt a huge difference in handling, particularly in one direction versus the other, I felt REALLY uncomfortable riding on that tire. I've also ridden on a street tire that had a ton of freeway miles on it and was squared off (flat in the middle) and I found that quite disconcerting, too, it was hard to turn initially then dropped rather suddenly into the lean and I didn't feel like I had good control of my lean angle.

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