Tire talk - mainly for trackdays

This information was posted by a veteran racer on another forum. The post is a little confusing, but the message is clear.

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TRACKDAY TIRE WARM-UP PROCEDURE/CONSIDERATIONS

The problem of "cold tire crashes" at trackdays is one that seems to show up time and time again, regardless of whether the outside temperatures are in the 60's, or in the 90's+. From the observations that I've seen of trackday/track school crashes over the last 10 years, I'd conservatively estimate that at least 50% of these crashes are in some way related to tires not being fully up to temperature. In hoping that a little sharing of a bit of personal experience on this topic might potentially cut down on this statistic at future trackdays, I'm posting the following.


TRACKDAY WARM-UP SCENARIO #1
(NOT to do version)

Lap 1 of a trackday session (afternoon session):

Rider circulates the track at a moderate and gradually building pace, leaning the tires over off center by the following incremental amounts:

1st right turn: 20%
2nd right turn: 25%
1st left turn: 20%
2nd left turn: 25%
3rd left turn: 30%
4th left turn: 35%
3rd right turn: 30%
etc ..... etc. ...... etc. .......
last left turn for lap 1: 50%
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Lap 2 of session: (rider assumes after completing one full lap tires are warm)

1st left turn: 60%
1st right turn (Turn 3): 80% ................ (CRASH!!!!)

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In this scenario, the problem is that despite the bike having completed a full lap, (or maybe even two laps, if traffic restricted speeds during that time and limited the maximum lean angle incrementally obtained), 50% of the sides of the tires have not yet made contact with the pavement. As such, despite the middle 50% of the tire being relatively "warmed up", the part of the tire that will be called upon to provide traction when leaning the bike that added 30% into the 1st righthand turn on the 2nd lap, will still be "cold". The outcome? The tires let loose just like the bike was starting on its very first corner, on its very first lap ...... because in the view of this previously untouched portion of the tread surface of the tire .... that's exactly how it sees things. Make sense?

The secret to avoid this situation is to recognize the fact that only the portion of the tire that has actually made contact with the pavement up to that point will have developed any heat (i.e "traction potential"). The rider must then make it a religious ritual to never adding in more than a couple of degrees of additional lean angle from one corner, to the next adjacent corner, regardless if it's the first lap of a session, or the second.


TRACKDAY WARM-UP SCENARIO #2
(RECOMMEDED version)
Lap 1 of session:

1st right turn: 10% lean
1st left turn: 10% lean
2nd right turn: 15% lean
2nd left turn: 15% lean
3rd right turn: 20% lean
3rd left turn: 20% lean
etc. ... etc. .... etc. ...

Lap 2:
1st left turn: 50% lean
1st right turn: 50% lean
2nd left turn: 55% lean
2nd right turn: 55% lean
etc. ... etc. ... etc. ...
Last corners of 2nd lap:
95% lean
100% lean

If for some reason (slower riders encountered, excessively cold or any dampness of conditions, etc.) I am not able to incrementally increase the lean angles in those very "baby step" increments in all corners along the way, I will simply make it a point to add another lap to the warmup process before committing to the more extreme lean angles.

Hopefully for those of you that have had the misfortune of experiencing a trackday crash where the lack of full traction being available across the entire width of the tread area of a bike's tires was a primary contributing cause, the application of the incremental lean, two-lap full warm-up procedure I've shared above might be helpful in preventing a future reoccurrence. For those of you fortunate enough to not yet have experienced this, perhaps reading this (and religiously following it in the future) will prevent a first time get-off from this cause ......

Gary J
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For those who think that weaving left to right helps to warm up your tires...

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Weaving Makes For Good Collisions
By Dave Swarts

Weaving to warm tires is a fiction that just won't die. All sorts of riders who should know better can be seen weaving wildly on warm-up laps, and we've seen plenty of collisions and near-misses caused by one guy weaving into another guy on a warm-up lap. Yet some riders persist in the belief that weaving actually does something other than create a hazard. So, since we had gathered a test bike, a test rider, all sorts of measuring instruments, some extra tires, and had a track to ourselves for our big tire test (Roadracing World, January, 2000), we decided to test the effects of weaving on motorcycle tire temperatures.

We conducted this experiment using Mark Junge and his 1999 Kawasaki ZX-6R, at Oak Hill Raceway. Michelin tires were used for this test, the front a standard Pilot Race, and a Pilot Race "W" on the rear. First, we measured the cold tires' core temperature in the middle and on both sides of the tread, front and rear. We then sent Junge onto the track to ride slowly in a straight line and then measured the tire temperatures. Then we instructed Junge to weave aggressively from turn eight to turn two and back again (approximately one-half mile), and measured the tire temperatures again to see how much heat was produced in the tires.


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Weaving on the warm-up lap won't warm-up your tires. It will, however, make it easier for you to run into other riders on the warm-up lap. Photo by Brian J. Nelson.


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Next, we let the Michelins cool off. We then heated the tires on warmers for 45 minutes per Michelin's recommendation and took the tire temperatures. Then Junge went out and did the same weaving and temperatures were taken again to see if additional heat was built up or if heat was lost.

Next, Junge was sent on a standard warm-up lap. We then quickly measured the tire temperatures. Then Junge did another 1.8-mile warm-up lap, this time weaving, and we measured the temperatures again to see if weaving built additional heat when compared to a standard warm-up lap, kept the heat in, or lost the heat. Then we did the half-mile of weaving again before taking the tire temperatures yet another time.

To complete our test of tires and temperatures, we sent our rider out on two normal warm-up laps. Once back on the starting grid, we stopped the bike with the tires remaining on the pavement just as you would sit on a grid with the 3-minute board in the air. Then we measured each tire, as quickly as possible, to see how quickly the tires lost the heat built up on the warm-up lap.

The first thing that we discovered while trying to take the temperature of the cold tires was that the sun has a significant effect on a tire's temperature. Our test bike was under a canopy but the front tire was still in direct sunlight on an 88-degree, Texas afternoon. Just from sitting in the sun, the front tire had between 10 to 20 degrees more heat at the tread's core, not the surface.

When Junge rode in a straight line at line at approximately 40 mph for about a half-mile, the shoulder of the tire that was in the shade remained at 85-88 degrees F. The temperature at the center of the tires went up slightly while the shoulder of the tire facing the sun also started picking up heat. Then our rider went on his weaving course and came back. Once again the side of the tire facing away from the sun and the center changed very little. The side of the tire facing the sun continued to gain heat. We attributed this solely to the sun as Junge was careful to weave equally hard on each side of the tires.

Junge went back to his task of learning Oak Hill on his "A-bike" while we took the weaving test bike back under the canopy and applied Tyr Sox tire warmers for 45 minutes. After the warmers, the rear tire had about 129 degrees F across its entire tread while the front held 171 degrees F on the right, 175 degrees F on the left, and 182.4 degrees F in the center. Both warmers were on for the equal amounts of time.

Just as I was organizing a theory into how the tire warmers have equal heating elements but the (120) front tire has less surface than the (180) rear tire, I noticed that the bike had been put back in its original parking spot with the front wheel in the sun. Although I can't rule out my equal tire warmers versus different-sized tires theory, I can't rule out that the strong sunlight increased the effect of the warmers.


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The most effective way to warm-up tires is to park the bike in the sun and use tire warmers. This is Miguel Duhamel's Honda RC51 at Daytona. Photo by Brian J. Nelson.


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As soon as we took the post-warmer temperatures, Junge went out to do the same exact weaving course. The right/away-from-the-sun side of the rear tire lost 12 degrees of heat. The right side of the front lost 45 degrees. The center of the rear lost 5 degrees of heat. The center of the front lost 43 degrees. The left side of the rear tire that was facing the sun stayed steady at 129 degrees while the left front only lost 36 degrees. Once again weaving did not build or hold the temperature. The sun had more effect than weaving.

As soon as these temperatures were taken, Junge was sent off to do a normal hot lap on the twisty, 1.8-mile course. After the hot lap, the heat in the rear remained fairly constant, cooling just a few degrees. The front continued to steadily lose its significant tire warmer heat. However, the left sides of the tires were the warmest parts. We could not attribute this to the sun because throughout our two-day test, tires always recorded higher temperatures on their left sides after doing any laps at speed on the track.

Then, we sent Junge to do an entire lap of weaving. Again, the weaving failed to hold heat anywhere on the tire. Then Junge once again did his straight weaving test, and the tires began cooling rapidly. In fact, during weaving the tires lost heat as rapidly or more rapidly as just standing still.

For our final test, we sent Junge out to do two laps to get some heat in the tires. Then as the bike stood still on the racing surface just as it would on a grid, we measured how quickly the tires lost their heat. I had originally hoped to measure the six spots on the tires every 10-15 seconds. That proved too ambitious. I ended up measuring each spot every 45-60 seconds. Next time, I'll have two pyrometers. This was very interesting, though. While the center and right sides of the tires lost 10-12 degrees over a 4-minute time period, the left side of the rear lost very little heat and the front gained heat from the direct sunlight.

Here are some conclusions. Tire warmers will produce the highest pre-race tire temperatures. During the tire comparison test consisting of 8-10 laps at 100 percent speed, we sometimes did not record temperatures higher then straight off the warmers. So the best way to warm tires is to use tire warmers.

The second-best way to warm tires is to take a hot lap. As powerful as the sun proved to be, a good hot lap produced more heat than time in the strong sun, and it's quicker, too.

The third-best way to warm tires is to leave the tires in strong, direct sunlight. Just don't forget to get both sides.

But weaving, no matter how aggressive your lean angle and your speed or how long the distance covered, does not build any additional heat in a tire!

So now, we will hopefully never see another unfortunate accident from useless weaving on a starting grid or pit lane. Case closed.


Comparison Of Tire Temperatures As Affected By
Warming Methods And Ambient Conditions
Ambient Conditions And Temp Probe Location In Sun Rear, Left In Sun Rear, Center In Shade Rear, Right In Sun Front, Left In Sun Front, Center In Shade Front, Right
Warming Method
Cold Tire 85 87 86 94 105 98
Straight line, slow 89 98 85 95 106 87
Weave aggressively 96 99 87 99 104 88
Tire warmers 129 130 127 176 182 171
Warmers and weaving 130 129 115 139 139 126
Std. warm-up lap 124 122 122 130 126 120
Weave, 1.8 mile 121 118 120 129 117 119
Weave, 0.5 mile 118 115 110 114 109 113
Comparison Of Tire Temperatures As Affected By
Time On Grid And Ambient Conditions
Start Temp 128.6 123.6 120.8 129.0 116.4 111.6
+0:45 seconds on grid 127.6 117.0 115.4 128.6 115.6 110.6
+1:45 seconds on grid 126.8 116.0 114.6 128.2 113.6 110.6
+2:45 seconds on grid 125.4 115.0 112.0 127.2 113.6 106.0
+3:45 seconds on grid 124.0 111.8 108.2 125.6 113.0 104.8

All temperatures in Fahrenheit. Track temperature was 86 degrees; ambient temp in shade was 88 degrees. Cold tire pressure was 30 psi in front, 28 psi rear. Tests were conducted on Michelin Pilot Race tires.

Here is a more scientific article.

Motorcycle Tire Basics

How To Properly Warm Up Your Tires (SPORT RIDER MAG)
By Lance Holst

Few aspects of riding technique are as clouded with the dark specter of myths, old information-or just plain bad information-than how to warm up new tires. In fact, many of us, me included, still use the misleading terminology of "scrubbing" in new tires, which wrongly implies that the surface of the tire itself needs to be scrubbed or abraded to offer traction. While this may have been the case long ago when manufacturers used a mold release compound, it most definitely is not the case today.

To clear up the issue of how to ride on new tires, we cornered Cristoph Knoche, the Racing Manager for Pirelli Tire North America's Motorcycle Division. Knoche has been with Pirelli for 13 years, working with the company's R&D department while involved with World Supersport, where Pirelli won the World Championship with Fabien Foret while battling against the other brands prior to the series adopting Pirelli as the spec tire for World Supersport and World Superbike. More than just a racetrack technician, Knoche also has first-hand experience with the prototyping process and development of special racing tires.

First off, Knoche quickly dispatched the old wives' tale that the surface of the tire needs to be scuffed or roughed up to offer grip. "Maybe it's coming from the old days when people were spraying mold release on the tread when the molds were maybe not that precise," Knoche speculates, "and the machinery was not that precise. But nowadays molds are typically coated with Teflon or other surface treatments. The release you put in there (in the sidewall area only, not the tread) is for like baking a cake, you know, so that it fills all the little corners and today that is done more mechanically than by spraying. The sidewall is important because you have all the engraving in the sidewall [with tire size, inflation pressure and certifications] and that you want to look nicely on your tire, so that's why we still spray the mold release there."

The next myth we see perpetuated nearly every time we watch the warm-up lap to a race. Riders begin weaving back and forth in apparent attempt to scuff the tread surface (which we've already discounted) and generate heat. The reality is that, according to every tire engineer that I've asked, there are far more effective ways of generating heat in a tire that are also much safer. Rather than weaving back and forth-which does little in the way of generating heat but does put you at risk asking for cornering grip from tires before they're up to temperature-you're far better off using strong acceleration and braking forces, and using them while upright, not leaned over! Acceleration and braking forces impart far more flex to the tire carcass, which is what generates the heat that then transfers to the tread compound as well (you often see Formula 1 cars weaving violently back and forth because automobile tires operate on a horizontal plane, so they have and use significant sidewall flex to generate heat).

All I can say is that you should trust the educated opinion of tire engineers over the old habits and superstitions of even the best racers. That said, I still-out of habit-occasionally catch myself weaving out of the pits on fresh rubber before chastising myself and then applying heavy yet smooth acceleration and braking forces into the tire while keeping the bike relatively upright.

If you're a racer, or a serious enough track-day rider to have tire warmers, Knoche recommends that you have them on the bike for a full hour to get not only the tread surface of the tire, but also the entire carcass and sidewall section, up to temperature as well. "With modern compounds," Knoche explains, "there are a lot of waxes and oils and (we) have to get them really to temperature. We suggest to get them up to around 165 degrees Fahrenheit. Because what happens is you have to warm your tire not only on the surface but what we look for is touching the wheel and you want that a little bit more than hand warm."

In addition to warming tires up before the session, Knoche also recommends that riders coming off the track get the warmers back on to prevent the tires from cooling and going through another heat cycle. "Even with the tire on the warmer all the time," warns Knoche, "it takes about two laps to get to the good compound underneath, a little bit."

It should be noted, as well, that unlike many tire brands that give suggested cold tire pressures, Pirelli prefers to set tire pressures after the tire is up to temperature (165 degrees F on a warmer or after 10 minutes of lapping the track). Knoche says that pressures vary slightly depending on track conditions and rider preference but that the Pirelli engineers prefer to run from 32 to 34 psi in the front and from 28 to 30 psi rear. They like to see between a 3 to five pound rise in pressure from the initial cold tire to one at 165 degrees or above.

It might follow that suggested cold tire pressures would start 3 psi below the pressure listed above, but Knoche wasn't comfortable making that suggestion. Instead, he recommends, as many tire engineers do, that riders, "contact our technical support people."

Many years ago I recall a coworker at Motorcyclist magazine telling me that it could take as much as 100 miles for a tire to truly break in and offer good traction. I doubted that it was true then and it certainly isn't true today. Knoche reaffirms that there's no need to believe that old myth that often left typical street riders riding away from the dealership on new tires literally white-knuckled with fear of the "treacherously slippery" tires.

"I would say nowadays if the surface looks like new-as long as you don't have contact cleaner on, no soapy water (often used by tire fitters to help slip the bead over the rim) or oil-there should be no concern," said Knoche. But that isn't clearance to simply go for it, either. "For sure a new tire, especially if you change the brand or even get a different production lot, it can be slightly different," Knoche said. "So I think that's more the concern people should have. Maybe with a new set of tires that's a new experience. Get the experience; it's like riding in a brand new car, you don't race around the first corner because you don't know what's going to happen."

Finally, there is the aspect of using race tires on the street. Interestingly, Knoche says Pirelli's street and DOT race tires should come up to temperature equally quickly and at no time does the race compound offer less traction than that of the street tire. However, this is not a statement that we feel can be safely applied to all brands of tires, as we've heard differently from tire engineers (not marketing managers) from other companies regarding their specific brand. Regardless, there are plenty of other reasons not to run modern DOT race tires on the street, not the least of which is tread life that can be as short as 300 miles of aggressive riding! That's a cost of well over $1.00 per mile. Such are the compromises required to run at the front of the pack in AMA Pro Racing competition.

"That's why we developed the Diablo Corsa III," said Knoche. " This tire has, in the rear, three compound sections. The center is a street compound but on the side you have about one and half inch, probably, of our race compound, which gives you a little bit more fun." Take a look at any competitive DOT race tire and you'll note the scarcity of tread grooves in general and the total lack of them anywhere near the edge, or shoulder, of the tread. Even for track day riders that may face damp or wet riding conditions without the luxury of a spare set of wheels with wet weather tires mounted up, Knoche recommends the equivalent of Pirelli Diablo Corse IIIs, "so that we don't have to change to intermediate or rain tires because they're designed for the street.

David,

Very informative post, thank you very much.:thumbup:

I think that building heat in the tires is very much mis-understood by most riders...myself included. I learned some things from this.....especialy the weeving part....I have never done that, but interesting to learn that it really does not help and only increases your chances of getting into an accident.....

:rockon:

Wavex said:

How To Properly Warm Up Your Tires (SPORT RIDER MAG)
By Lance Holst


The next myth we see perpetuated nearly every time we watch the warm-up lap to a race. Riders begin weaving back and forth in apparent attempt to scuff the tread surface (which we've already discounted) and generate heat. The reality is that, according to every tire engineer that I've asked, there are far more effective ways of generating heat in a tire that are also much safer. Rather than weaving back and forth-which does little in the way of generating heat but does put you at risk asking for cornering grip from tires before they're up to temperature-you're far better off using strong acceleration and braking forces, and using them while upright, not leaned over! Acceleration and braking forces impart far more flex to the tire carcass, which is what generates the heat that then transfers to the tread compound as well (you often see Formula 1 cars weaving violently back and forth because automobile tires operate on a horizontal plane, so they have and use significant sidewall flex to generate heat).

Click to expand...

This say's it all...:rockon:

David,

Thank you for this great information. I have been guilty of trying to warm up tires the old fashioned way. I weave more when I just went through gravel and want to try and clear any bits off before I go hard on them. This busts a lot of myths about scrubbing and warming.
Thanks for a great post!

Cliff

Great info David, thanks! I've always done the two lap rule of thumb. I've no idea where I picked it up but it works.

I'd like to try a set of tire warmers some time but that would mean buying a generator.

Yeah tire warmers = $500 for the tire warmers + $1000 for a good generator = $1500... that's 10 trackdays!!! I will stick with putting my tires in the sun between sessions and riding "mellow" for a lap or 2

Does Size Matter
Squeezing a wide tire onto a narrow rim can be a big mistake. Here's why.
By Andrew Trevitt


Those low-profile 190-series tires sure look gnarly on the back of a sportbike, and we've seen them pinched onto all sizes of rims. But in reality, a 190/50-17 fits properly only on a 6.0-inch rim, and cramming it onto anything smaller severely changes its profile.

As an experiment, we mounted a 190-series Metzeler Rennsport onto our F4i's 5.5-inch rear wheel and took some measurements. Compared to the correctly sized tire on the same rim, the 190's profile closely matches the 180's near the edges of the tread, but is much lower in the center area-equivalent to about a 6mm change in ride height. Effectively, the wider tire will give more rake and trail when the bike is vertical, while keeping close to the original geometry when the bike is leaned over. Accounting for one (by changing ride height) will unduly affect the other.

Following our test with the Metzeler Sportecs, we slipped a 190/50 rear Sportec onto the F4i and rode a portion of the test loop for a practical comparison. With no changes to suspension or geometry, the F4i felt substantially different with the wider tire. With the bike straight up and down, steering was slightly sluggish in comparison, but just off vertical, the F4i was quite tippy and darted into corners. The light, neutral steering of the Sportecs was completely changed and the bike lost its balanced feel. The sensation was very much like riding on a tire squared off from too many freeway miles. At higher lean angles, performance was less affected, although making transitions from side to side was unpredictable. And, contrary to the popular myth that the wider tire puts down a bigger footprint and gives more traction, we felt no improvement in that department from the properly sized tire.

We've experienced similar changes with a 180-series tire on a 5.0-inch rim meant for a 170-series bun. Tire engineers work hard to design and match front and rear profiles for characteristics that we sometimes take for granted. Upsetting that balance is surprisingly easy and you should think twice before sacrificing your tire's performance for appearance's sake.




This story was originally published as part of the tire test in the June 2002 issue of Sport Rider.

nccoder said:

David,

Thank you for this great information. I have been guilty of trying to warm up tires the old fashioned way. I weave more when I just went through gravel and want to try and clear any bits off before I go hard on them. This busts a lot of myths about scrubbing and warming.
Thanks for a great post!

Cliff

Click to expand...

i agree.. very good info. i too weave a bit but i do it mostly to get the dirt off as my drive is grass dirt or after going through dirt just to make sure that if i have to do emergency turn after there is minimal dirt on them