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Warming Tires


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Hi All (and Steve),

 

I wanted to get a thread going, though we have touched partly on this already, about how tires are warmed. We do not have the option to use tire warmers at the school for the coaches, and students riding the school bikes, so this is of interest to many.

 

My understanding is that in essence tires warm from the inside out, the carcass flexing. Many have talked about friction/contact with the surface warming the tires, but my take is that this actually cools the tires down unless it is very hot.

 

Maybe Steve can set us straight on this, including when will track temp help actually warm the tires.

 

I'd also like to have Steve touch on warming both sides of the tires, as this is an issue we have seen often: riders start out of the pits on cold tires, make a few turns on lets say the right side, keep picking up the pace, hit the first left turn and they are down.

 

Hope these questions are clear Steve, let me know please.

 

Best,

CF

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A nice topic, Cobie. Here's my take... each oem is different - to a point (according to a Dave Moss video on tire wear).... some perili's cool down at 'excessively' low temps. Although, I do understand his viewpoint is from a suspension/tire reading perspective.

 

Aside form the excellent stability points Steve made regarding pressures; I too have been under the impression that heat builds up from friction. So, a lower psi will give a greater contact patch and therefore more friction, thereby heating the rubber faster. I also think that a lower psi, whilst leaned over, adds to rubber deflection, possibly resulting in some internal friction (inside the rubber itself)... which might add to the temp increase; maybe???

 

I'd be interested in the heat passing from the engine, to chain, to axel, to rim, to tire. Could there be some sort of correlation? How would the rim's material play a part, either with conductivity or dispersion?

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I'd be interested in the heat passing from the engine, to chain, to axel, to rim, to tire.

I would doubt much heat is going to transfer through the chain all the way into the tire, but we'll see what Steve thinks. But one thing related I wondered about was- why not have the exhaust blow directly on the tire? That would heat it up in a hurry! (I suspect the fumes will not do nice things to the rubber.)

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There are at least two ways a tire can heat up: heating up from the deformation (internal heating) and heating from the tire spinning (if you don't believe this, go and find any video of Gary McCoy riding the RedBull Yamaha GP500's from around 2002-2003 - he would spin the rear tire so much it would literally lay down a blue smoke!).

 

Steve is the expert here, but my understanding is that the primary heating action is from the tire deformation - not the abrasion against the surface.

 

 

Kai

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I'd be interested in the heat passing from the engine, to chain, to axel, to rim, to tire.

I would doubt much heat is going to transfer through the chain all the way into the tire, but we'll see what Steve thinks. But one thing related I wondered about was- why not have the exhaust blow directly on the tire? That would heat it up in a hurry! (I suspect the fumes will not do nice things to the rubber.)

 

 

Probably not, but I'm still interested with how/what effects the rim plays.... maybe the rim heats up due to the heat generated by the tire.

 

For teh exhaust, something I've thought about for years, maybe the gap between the tire and pipe is sufficient to disipate the exhaust's effects, or maybe the wind is the buffer.

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I did talk with one of the Dunlop engineers, and they don't even measure the external temp, just the internal temp. Very interested to see what Steve can fill in here. But we are getting closer to x-mas, maybe he'll take a few days off! I'm going to :).

 

CF

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Tires heat up from using them or by using a tire warmer. I am not trying to oversimplify it, but that is what is happening.

 

You could try to pick it apart and say that X% is from the construction flexing and Y% is from the surface of the tire rubbing or spinning on the pavement, Z% from this and so on. Doing that would not change the reality that when you ride on the tire it gets hotter, and when you rider faster it gets even hotter.

 

Some would like to try to regulate the temperature of the tire via the pressure, and this would be a wrong action. Yes you can slightly regulated the running temperature of the tire by adjusting the pressure, but again as stated before you would be affecting the overall grip and stability of the tire much more than you would be changing the temperature.

 

The tire is NOT affected via the engine heat through the counter shaft, primary sprocket, chain, rear sprocket, axle, spacers, bearings, rim hub, spokes and the outer rim. This is just to far for the heat to travel to be of ANY consequence at all. If the outer rim gets hot is is becasue the tire is hot.

 

The most significant thing that generates heat is the construction flexing and moving against itself. Different constructions generate different levels of heat. Different air pressure can change where the heat is located or how spread out it is across the tire.

 

Another factor is how thick the rubber is. Thicker rubber = more heat, Thinner rubber = less heat (given all other factors are the same).

 

Another factor is if the tire is spinning on the pavement, abrasiveness of the pavement, temperature of the pavement, bike weight, rider weight, chassis setup and lap times. All these things contribute in some way to the tires temperature.

 

IN the real world, if you don't use warmers, you should take 2 laps to warm up your tires before you start to put in fast laps. If you come off the track for a break, you will need to put heat back in the tire again before going fast again. You must be the judge of how much heat is lost during your break and how much heat you need to put back in them before going fast. There is no magic equation for this, you need to pay attention and act accordingly.

 

So lets look at a couple of examples and real world situations:

 

1) Barber Motorsports Park, 40deg F, the wind is blowing, R6, slow rider, is riding for 12 laps and all is going well, then he comes in the pits and take 10 minutes to eat a power bar and drink water. I would recommend taking 2 laps to warm the tires back up. The cold wind will drop the temp fast, and the tires were probably not all that hot off the track being he is a slower rider.

 

2) Willow Springs, 100deg F, sunny, no wind, R1, fast track day rider, comes in after a 20 min session and is going out after a 20 min break. I would recommend 2-4 corners of warm up. The tires did not cool much in the heat and just a couple of corners and the rider will be back doing fast laps.

 

As you can see there are many variables in play. You must use your head and experience to be a good judge of the situation.

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Great data Steve!

 

I would like to comment on the number of laps to get the tire warm. I've done a number of cold and/or windy days and can say for sure, that 2 laps may not be enough. There are of course different factors. Two laps on the infield course at LVMS is like doing a half a lap at VIR. :)

 

There is a tech on how I warm up the tires (without a tire warmer).

 

1. Gradually increase the lean angle from turn to turn. If the tire is only flexing near the center, then that's where it will be warmest. So gradually warm up the whole tire. When doing this, you may discover that when you leaned it over 2 or 3 more degrees than last corner, that you actually felt them slip just a touch.

2. Do this lap to lap until you don't have that "slip". Again, depending on ambient temp, wind-chill, length of track (and tire constructions too, slick vs dot tire) this could be 2-3 corners to even a half a dozen laps.

3. Now this one may be arguable, but I've had success with it... I do the same as above but I do get the tire spinning a bit out of the corner. On the drive out (picking the bike up) as there is a decent load on the tire (flexing) I increase the throttle just enough to get it squirming/slightly spinning.

 

Really, if you don't have tire warmers - YOU are the tire warmer. Pay attention to them!

 

Best,

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Another excellent post Steve.

 

One point Pete brought up, and wonder if you have anything more to add is warming both sides of the tire. Here is something we have seen: Rider goes out, cool day, cold tires (no warmers) takes 2 right hand turns medium speed, gradually increasing his pace, then comes to a left and goes a little faster and crashes.

 

Can you elaborate (if needed) on this point?

 

Best,

CF

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Another excellent post Steve.

 

One point Pete brought up, and wonder if you have anything more to add is warming both sides of the tire. Here is something we have seen: Rider goes out, cool day, cold tires (no warmers) takes 2 right hand turns medium speed, gradually increasing his pace, then comes to a left and goes a little faster and crashes.

 

Can you elaborate (if needed) on this point?

 

Best,

CF

 

 

Great point Cobie!

 

Yes, you must take into consideration the left and right sides of the tire. The 2 lap recommendation is a general recommendation. The rider must adjust this depending on the track. In Cobie's example you can clearly see the rider was NOT taking into consideration that the LEFT side of the tire cold, but he rode it like it was partially warm.

 

Certainly if the track is mostly right handers, then he must take a little more care on the left handers till things are warmed up.

 

Don't think that just because you did 6 left handers the whole tire is equally warm. Yes, heating up one side will put some heat in the other side, but not always enough. You need to warm each side up.

 

Keep in mind that on most tracks there is an uneven amount of right and left turns, thus the temperature from the left and right sides may vary after a session.

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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

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generally, how hot should tire warmers get the tires? for a fast intermediate track rider, on a day say in the 65 to 70 degree range, how long do you think the tires would hold the heat, in the pits and gridding up?

 

We recommend warmers to be set about 158 deg F, (70c). http://www.dunloprac...com/Warmers.pdf

 

As for your question about temperature and time, it would be very nice if I could give you a nice neat answer and put it all in a perfect uniform exact procedure, but this is not possible with all the factors involved.

 

You need to take into consideration all the factors; ambient temperature, track temperature, wind, how long off the track, how slow the last lap was, your lap times, and others. These things need be taken into consideration. To benchmark your situation you need to ask yourself how much grip do you need (or are likely to need), compared to how hot you got the tire in the last session, how long its been off the track, wind, and other factors above, then make your adjustments accordingly. (adjustments = how you are going to put heat back in the tire, via easy laps or tire warmers)

 

Don't think that 158 def F is OK, while 157 deg F is not OK and you will immediately fall down. This is not the case. Tire temperature is on gray scale, sliding from more white to more black. It's not like a light switch, on or off. It's more like a dimmer switch, that transitions from dark to full bright.

 

Slower riders will never see the highest temperature of the tire because they are going slower. And in turn they will never NEED the highest temperature because they are not going fast enough to need it. This flows hand in hand. The faster you ride, the more you will need higher temps.

 

The important thing is to not try to fit this all into a neat little box of yes or no, on or off, white or black. You need to use your judgment, observation and feel for what is going on. I cannot give you an exact answer of "how long do you think the tires would hold the heat", simply because there are too many variables. My best advice is to pay attention to the conditions and draw on your experience. If it was a 70 deg day and you came off the track for 10 min, would you go at race pace into the first turn, or give it a couple of turns? What about 11 min, 12 min, 13 min? Look at this issue from that point of view.

 

I have observed top riders leave the pits on cold tires and be 25 sec off the pace on the out lap, and 15 sec off the pace on the second flying lap. Don't try this at home, ;) But it is possible.

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generally, how hot should tire warmers get the tires? for a fast intermediate track rider, on a day say in the 65 to 70 degree range, how long do you think the tires would hold the heat, in the pits and gridding up?

 

We recommend warmers to be set about 158 deg F, (70c). http://www.dunloprac...com/Warmers.pdf

 

As for your question about temperature and time, it would be very nice if I could give you a nice neat answer and put it all in a perfect uniform exact procedure, but this is not possible with all the factors involved.

 

You need to take into consideration all the factors; ambient temperature, track temperature, wind, how long off the track, how slow the last lap was, your lap times, and others. These things need be taken into consideration. To benchmark your situation you need to ask yourself how much grip do you need (or are likely to need), compared to how hot you got the tire in the last session, how long its been off the track, wind, and other factors above, then make your adjustments accordingly. (adjustments = how you are going to put heat back in the tire, via easy laps or tire warmers)

 

Don't think that 158 def F is OK, while 157 deg F is not OK and you will immediately fall down. This is not the case. Tire temperature is on gray scale, sliding from more white to more black. It's not like a light switch, on or off. It's more like a dimmer switch, that transitions from dark to full bright.

 

Slower riders will never see the highest temperature of the tire because they are going slower. And in turn they will never NEED the highest temperature because they are not going fast enough to need it. This flows hand in hand. The faster you ride, the more you will need higher temps.

 

The important thing is to not try to fit this all into a neat little box of yes or no, on or off, white or black. You need to use your judgment, observation and feel for what is going on. I cannot give you an exact answer of "how long do you think the tires would hold the heat", simply because there are too many variables. My best advice is to pay attention to the conditions and draw on your experience. If it was a 70 deg day and you came off the track for 10 min, would you go at race pace into the first turn, or give it a couple of turns? What about 11 min, 12 min, 13 min? Look at this issue from that point of view.

 

I have observed top riders leave the pits on cold tires and be 25 sec off the pace on the out lap, and 15 sec off the pace on the second flying lap. Don't try this at home, ;) But it is possible.

 

It is great to see such highly qualified info being made available.

I'll be following this Forum, that is for sure!

 

I'm a mere intermediate level half century aged track day rider on a Honda 919.

I do not want to bin my bike.

I have managed over 1000 miles of track day mileage with no getoffs so far.

I am absolutely fiendish about warming up the tires.

I often start at the back, go easy on lap 1, speed up some for the second, start dialling it up on the third, and find by the end of the 4th lap the tires seem to be as grippy as I can get them.

I notice a big difference from cold pavement cold air days to hot pavement sunny hot air days.

Less grip = slower pace, the laws of physics being what they are.

I'm amazed at how many intermediates have getoffs in the first few laps, especially on cold days.

I happen to be on Michelin 2CTs.

 

Picking up from one of the other threads, I'll also note that I observed a huge change in rear tire pattern wear as I was sorting out my rear suspension set up. I have a Penske on it. Absolutely amazing, as the rear got close, the tire suddenly looked better. I had some major gremlins to chase away.

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  • 1 month later...

Steve: Sorry if this has been asked already -- I looked, but could not find this question asked or answered.

 

Does it make any sense to use tire warmers on a Q2 -- I'm considering doing my first novice race and would like to be able to avoid two laps to warm them up. I know it is a street/track tire and have heard that it is either a bad idea to use warmers on these types of tires or that it doesn't do anything to help out with traction even at the early stages -- but as with everything else there are too many myths out there for me to know. If it does make sense, should one use low or high temp on a dual temp warmer?

 

I want to go with D211GPAs next tire change, but I think I still have 2 or 3 more track/race days on the Q2s that are currently on the bike. Thus far Q2s have been giving me very good traction with no problems at the speeds I can currently ride, but I always gradually build speed the first 2 laps on track days to warm them up. If a warmer would alow me to ride a little harder for the first two laps in a race, I may choose to use them in that first race. Otherwise, I guess I have to go to those D211GPAs sooner.

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Steve: Sorry if this has been asked already -- I looked, but could not find this question asked or answered.

 

Does it make any sense to use tire warmers on a Q2 -- I'm considering doing my first novice race and would like to be able to avoid two laps to warm them up. I know it is a street/track tire and have heard that it is either a bad idea to use warmers on these types of tires or that it doesn't do anything to help out with traction even at the early stages -- but as with everything else there are too many myths out there for me to know. If it does make sense, should one use low or high temp on a dual temp warmer?

 

I want to go with D211GPAs next tire change, but I think I still have 2 or 3 more track/race days on the Q2s that are currently on the bike. Thus far Q2s have been giving me very good traction with no problems at the speeds I can currently ride, but I always gradually build speed the first 2 laps on track days to warm them up. If a warmer would alow me to ride a little harder for the first two laps in a race, I may choose to use them in that first race. Otherwise, I guess I have to go to those D211GPAs sooner.

Steve actually answered this question for me, even though I was asking something different at the time :) .

 

Note: I noticed you mentioned "I was planning on getting Q2's.... mainly because they have good rep, don't require tire warmers", I don't know where you got the idea that Q2 does not need warmers and other tires do. All the warmers do is give you the opportunity to go fast on the fist 2 laps, instead of taking 2 warm-up laps. All the warmer does is put heat in the tire so you don't have to on the first 2 warm-up laps.

 

You can run a racing tire on a track day without warmers with no problems, as long as you take 2 laps to warm it up before you get going fast.

Although it likely would benefit us for Steve to provide his usual wisdom, I think this provides the info you were looking for. Use the warmers if you don't want to use laps to warm the tires, regardless of whether it's Q2's or D211GPA's.

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