New Hoosiers not working for me

[wyztek]

My old Hoosiers and my old Goodyears are still faster. This the first C3000 set that I have run and they are about a second a lap slower for me. Can anybody give me advice on differences in setup ie: different tire pressures, different camber, different spring rate? The main problem seems to be lack of grip at the rear. And in one corner, I seem to be getting skipping at the rear end.

[budawe]

The construction of the side walls has evolved over the years and you might have to look at air pressure reduction for help. The new tires take a while to bed in and heat cycling them prior to full session use is critical. The new construction appears to last a bit longer but require more work up front.

Without knowing more about your car, wish we had talked at Mission a couple of weeks ago, it's hard to say what to change. If the car is skipping, my gut says to start with air pressure. I typically scrub new tires with high pressure to prevent overheating but go to 18f / 20r afterwards. With a bumpy track like mission 17/19 or even 16/18 might be better.

[wyztek]

Those are good points. Unfortunately, my air pressures are in your ball park. Some other's advice said that maybe my droop is to low. I try for about 0 to -1 degree. Others say that with -5 camber I should be setting the droop to about -2. Do you concur?

The other possibility that I was sold older C3000s that had not been stored properly. The sidewall is incredibly stiff and impossible to mount with a manual tire changer. I get durometer readings of about 70.

The serial number on the tires are YC84. Can anybody tell me when they were made?

[BLS]

email Hoosier.

[Doug Fisher]

On my Swift, I run R35's and after talking to the 'Hoosier Guy' I have been running them cold at 15/16 psi....seems to work well.....

[Tiago Santos]

I think I remember hearing that the newer tires had stiffer sidewalls and were harder to mount. I doubt they'd have been stored so badly as to affect the lap times that much!

I'd try less rear camber and a smaller gap between static and droop camber angles.. No wait, do the opposite!!

[dc]

I think FV and FF cantilever tires may be very different for setups.

[smsazzy]

What kind of car?

On my Vortech I would shoot for a 2.5 window between camber and droop. Sometimes a little more or less.

So -4.5 camber, -2.0 droop was my starting point. I ran as low as -3.75 camber but never higher than -4.75 to tune for a given track, or condition.

[budawe]

My initial response is that your droop may be a bit too positive. A negative behavior of swing axles is that tire patch is in a constant state of change reducing mechanical grip. Running high droop, meaning close to static camber, while reducing overall travel, tends to make setup window rather narrow. I prefer strong rebound control to slow the rate of camber change and allow me to drive around the inherent issues with the rear suspension. For the same reason, I prefer a soft landing on the droop. Thanks to the "Brother's Sweeny," I use a spring instead of a rubber on the droop rod.

I may have been a bit too brief on my tire pressure advice. If one decides to run lower pressures, patience will be required to have consistent grip. All cars go off a bit towards the end of a session. If your starting pressures are too high, the tires will crown when hot and reduce the contact patch. Go too soft and you'll likely overheat the tires. If your car gets "skippy" and won't settle down mid turn, chances are the initial pressure is too high. If the car squirms around and is hesitant to take a set, then the tires may have been overheated. I know this sound a bit intuitive but without testing, with tire temps and pressures, you'll have to rely on your butt and feeling what the car wants.

Good drivers can drive around issues, but if the car is inconsistent, it will be difficult to drive. Get the car to do the same thing most times and you'll go faster.

[Amon]

Brian,

When you mean "running high droop, meaning close to static camber, while reducing overall
travel", are you referring to the droop being close to the camber degree's such as a 4 deg.
rear camber and 2.5 deg. droop, or the opposite such as a 4 deg. camber with 0- 1 deg. amt.
of droop??? Big spread or little spread across the range??

Thanks!

Mark

92' Protoform P-1/2

[budawe]

All droop contol should end in some state of negative camber. I refer to high negative camber as high droop. Sorry for the confusion. Some folks run droop close to 50% of total negative. Meaning, that if you run 5 static, the droop is 2.5 negative. Data has taught us that most turning vees hike fairly quickly into droop mode. Left uncontrolled, positive camber will be achieved and provide for a lot of excitement. The droop rod on a vee controls camber while in a turn, and will interact with oversteer tendencies of our cars. Finding a balance really depends on how well the front end is working. If you car turns in really well, then higher droop negative camber can be used. Cars that turn well tend to like higher camber readings on droop to catch the quick change in direction. Most zero roll cars tend to understeer and we use the droop rod to reduce droop camber to loosen the rear enough to allow the car to rotate and minimize exit push.

I recommend that once the static camber is achieved, the spring perch should be left alone. Using the pushrods for adjustment will directly effect droop. Changing the spring perch, not only changes two things, a bad thing, you won't see a linear and direct effect on droop. I prefer working with the pushrods cause your crew can do it in just a few seconds during a session.

[Hardingfv32]

The construction of the side walls has evolved over the years and you might have to look at air pressure reduction for help. .... With a bumpy track like mission 17/19 or even 16/18 might be better.

Why? Does stiffer side walls mean higher tire spring rates? The spring rate of these tires are in the 1500 lb/in range. Why do you think you are going to notice a pressure change if your suspension spring rate is in the 150 lb/in range? What is left for the tire to see after the suspension is done processing a bump, etc.?

I say the performance change you are getting is from changing the shape of the contact patch.

Absolutely no scientific data showing any benefit to race tire bedding or scuffing.

Brian

[Tiago Santos]

What's the spring rate of a flat tire?

[wyztek]

I appreciate all the advice. However, my most perplexing question that has not been directly answered is: does the C3000 require quite a different suspension setup compared to the older Hoosiers. For that matter, does every tire brand end up needing a unique setup?

Have I just been lucky to accidentally set my suspension to optimize the old Hoosiers?

[problemchild]

I appreciate all the advice. However, my most perplexing question that has not been directly answered is: does the C3000 require quite a different suspension setup compared to the older Hoosiers. For that matter, does every tire brand end up needing a unique setup?

Have I just been lucky to accidentally set my suspension to optimize the old Hoosiers?

Most of the comments have suggested playing with your droop settings. Try neg 1.5, neg 2, neg 2.5, etc until you have the balance you like. Playing with droop is usually all that's required when changing brands or models of tires. Takes a session or two. One degree of negative droop is not alot.

[Hardingfv32]

...does every tire brand end up needing a unique setup?

No

You can switch from American Racers, an extremely soft side wall tire, to Hoosier and have no balance issues.

I would say that the C3000 is not as durable as the past tire. If your balance is fine they last as long as before, but if your balance is flawed they will go off faster than the old style. They do not tolerate abuse. Probably a poor design for the majority of FV racers with ill handling cars and poor drivers.

Brian

[Daryl DeArman]

. Probably a poor design for the majority of FV racers with ill handling cars and poor drivers.

I think your filter needs to be cleaned and oiled...it's not real effective.

[Hardingfv32]

I have not found a filter for illiteracy, so do not expect a change any time soon from me. Being illiterate has never cost me anything academically or financially.

Brian

[Daryl DeArman]

Illiteracy? I was speaking of your charm and humbleness.

[Hardingfv32]

Yes, illiteracy, as I had no idea that was your point.

I did say 'majority', which can not be far from the truth. A little communication with the 'majority' and it becomes very clear that few have any clue.

Brian

[Daryl DeArman]

I was clear on what you meant and said. Someday when I'm older I'm sure my filter will be just as ineffective. I can already tell it's getting a little used up and I'm not even 50!

Now back to your regularly scheduled program...

[smsazzy]

Why? Does stiffer side walls mean higher tire spring rates? The spring rate of these tires are in the 1500 lb/in range. Why do you think you are going to notice a pressure change if your suspension spring rate is in the 150 lb/in range? What is left for the tire to see after the suspension is done processing a bump, etc.?

I say the performance change you are getting is from changing the shape of the contact patch.

Absolutely no scientific data showing any benefit to race tire bedding or scuffing.

Brian

I realize that this post may have been intended as one of your standard posts disagreeing with anything Brian McCarthy says, but your statement is quite untrue and shows a lack of understanding of what is happening to the chemical properties of a racing tire during the initial heat cycle, or scrubbing in, of a tire.

During the initial heat cycle, the chemical compounds withing the rubber change. The molecular strings that form the compounds of rubber actually tear apart and reform as longer chains. You can read about this in nearly any book or text that discusses racing tires.

The lengthening of the molecular chain strengthens the bond of the rubber. This does two things, it makes the tire last longer. (positive for us) It also makes adhesion higher. (also good for us)

There are three basic kinds of things the tire uses to hold the car to the pavement. Adhesive friction, which is pretty self explanatory, but is the property of hot rubber to stick to a surface like glue. Deformation friction, which is the tire deforming at the contact patch to take the shape of the road, and the tearing force of the rubber against the pavement. In tire books this is commonly referred to as wear friction. This tearing force is the issue at hand.

As sliding occurs, you are taking the tensile strength of the tire to a maximum point before tearing. The higher the maximum point is (higher tensile strength) the less the tire has a tendency to slide. This is the reason scrubbing in a tire gives both longer life, and higher grip.

Total friction is represented as T<friction> = A <friction> + D<friction> + W<friction> where A=adhesion, D=deformation and W=wear. If you can increase any of those, A, D of W, you can increase total grip.

We can increase W in a positive way by scrubbing a tire in. Conversely, W is decreased after we put multiple sessions on the tire and the rubber gets worn. We can change D, both positively and negatively with air pressure in the tire. A is pretty well set by the manufacturer.

[racerdad2]

That describes tire stuff better than the tire guys stuff. No book required. Thx !

[Hardingfv32]

During the initial heat cycle, the chemical compounds withing the rubber change. The molecular strings that form the compounds of rubber actually tear apart and reform as longer chains. You can read about this in nearly any book or text that discusses racing tires.

The lengthening of the molecular chain strengthens the bond of the rubber. This does two things, it makes the tire last longer.

You are simply regurgitating the same old story that has been told for years. I have never seen any scientific papers describing this process.

Lets question a few of your points:

If the initial heat cycle is so important why is it not specified exactly what temp to reach and how long to stay there? This is a chemical process after all. It should be well researched. Do any of the high dollar SCCA teams have a procedure for such a process? A way to measure the temp tire temp exactly and then maintain it for a specified time. What temp are we concerned with exactly by the way, surface or carcass? The fact is the tire manufactures do not have any scientific knowledge of the this scrub-in process that you are describing.

The tire compound is softest at the beginning of use and simply gets harder as its 'heat history' increases.

Why do all pro racers generally use stickers? If it works for them why not us? They have a different formulation? Why are amateurs not provided with this same 'no scrub' type of formulation? After all it is not like we have the time (sessions) to do tire scrubbing. Would this not be a useful product feature?

Brian

[racerdad2]

Well, if you're going to use logic & reason... I'm out....

[Tiago Santos]

I'm sure your buddies at f1technical will have some scientific research for you.

I'm also sure that Hoosier recommends scrubbing their tires out of respect for our elders. They clearly have no idea what's really going on. When are your monster tires(tm) coming out?

[smsazzy]

I realize that may have been one of your standard disagree with anything Stephen Saslow says posts, but I'll respond. I just explained the science, you dismissed it. That doesn't mean it isn't there, it means you have chosen to ignore it. Perhaps it has been the "same old story for years" because it is true.

The reason pro teams don't scrub them is simple, they are not typically concerned with longevity beyond the initial heat cycle. Additionally, they are constructed differently. A bias ply tire uses the initial heat cycle to break and reform the bonds, thus strengthening the bonds between the tire ply. I am not sure how this works in radials, as I have focused my research on bias ply tires, since that is what the class uses.

However, I have heard Steve Matchett, former F1 mechanic and current broadcaster mention that when F1 teams run a scuffed tire, they typically have a longer performance window, but have lost a bit of their initial speed. If true, that would confirm with real-world data that the scuffed radial tires do indeed last longer, however with a slight degradation in performance. They are, however, only using scuffed tires out of necessity due to regulations limiting the number of tires they are allocated for a weekend.

For more real-world FV data, I would cite Michael Veracins, who follows a very strict tire break in procedure. Considering his success and habit of testing, it would seem he has confirmed this to be true. Considering your total lack of meaningful results or even finishes in recent years, I would have to dismiss your assumptions as mere hearsay or speculation.

To answer your question regarding exact temperatures more directly, perhaps the exact temperature is not given because it is unimportant. Perhaps a wide temp range will work just fine to carry out the chemical process. Just as you can get paint to adhere and dry anywhere between 60-90 degrees ideally, and in practicality, anywhere from 40-120 degrees reliably would say that not all processes must be so exact. The key is heating the tire to normal operating temperature to carry out the process.

Now, if I may make a suggestion, instead of just dismissing what you are reading; perhaps try putting forth a rational thought or theory of what is going on instead of just accusing everyone else of being ignorant.

[grapefarmeral]

I believe if you look at Tire Rack website they discuss their "Heat Cycle Machine", so apparently someone knows some science about heat cycling. Scrubbing is just the poor mans way of heat cycling a tire.

Scrubbing a tire and not running it right away really makes a difference, although most of us don't have the time or $$$$ to do a test day (or scrub day) the weekend before a race weekend.

On a related note, a number of years ago at the ProVee race at Mosport we were talking to the Goodyear engineer. He was just back from 10 or 11 years in Europe doing Formula 1 and he related a story about Ayrton Senna. He told us that Senna could tell the engineers exactly where on the track the release agent was gone from the tires.... now there's someone that has a real feel for tires and grip..

[grapefarmeral]

By Tire Rack
Our heat cycling service begins by mounting the tire on an appropriate-width wheel and inflating it to the desired pressure. It is then placed in our heat cycling machine which has three rollers positioned at the corners of a triangle. The tread flexes where it comes into contact with each of the rollers, stretching the rubber compound enough to progressively bring it up to temperature all the way around the tire and across the tread. There is no artificial heat added by an oven, forced air or heat lamp.
The tread temperature is monitored with a pyrometer to confirm when the tire has reached the desired 170-180° F temperature. The tire is then dismounted and stamped as Tire Rack heat cycled. Since the minimum 24-hour waiting period typically occurs while the tires are in transit, the tires are ready to use when they arrive!
The only thing our heat cycling service doesn’t do is scuff in the tires.
Choices
While both ways will get the job done, many driving enthusiasts have chosen Tire Rack’s heat cycling service because it allows them to maximize their time on the track. They don’t have to invest in extra sets of wheels to manage multiple sets of tires, nor dedicate early weekend sessions to heat cycling new tires for the following days.
We’ve compared tire heat cycling done on our test track and in our heat-cycling machine. Measuring the tread temperatures with a tire pyrometer has confirmed we can’t quite duplicate the heat cycling machine’s controlled process with tires mounted on a car. We found on-the-car heat cycling was challenged by different driveline configurations (front-wheel, rear-wheel or all-wheel drive), vehicle weight distributions and competition camber settings that made it difficult to generate even tire temperatures on front and rear axle positions, as well as across the entire tread. Our heat-cycling machine allowed us to achieve appropriate and more consistent temperatures across the tire's tread without causing treadwear.
The cost of heat cycling is $15 per tire and is recommended by competition tire manufacturers.

[racerdad2]

Having read much of the tire mfgs tire break-in procedures & the chemistry behind it ( science ), their explanation is the first gentle heat cycle actually breaks down the rubber into short chain molecules & the gradual cooling off over 24 hrs actually transforms them into long chain molecules. This process does give the tire a longer useful life. Even our kart tires perform better, longer when we take the time to do this.... peace

[Hardingfv32]

I just explained the science, you dismissed it. That doesn't mean it isn't there, it means you have chosen to ignore it. Perhaps it has been the "same old story for years" because it is true.....

You stating something is science without any actual research proving that it is valid science. I have studied this subject and not found any science remotely backing up your statements. You should be ignored until you can validate you statements.

This is very similar to the state of the current criminal justice system where it has been determined that DNA is the the only scientifically valid form of forensic evidence. As an example all the non-DNA forensic work the FBI does lacks any scientific credibility. The same thing is going on with the subject of tire scrubbing even from the tire engineers. So Tire Rack charges $15 for some activity, does that validate it scientifically?

None of this would be hard to document in a highly controlled test, so why no published reports. Why no Master Thesis or Doctoral Dissertation on some aspect of the subject?

"...perhaps the exact temperature is not given because it is unimportant." It does not strike you as odd that the whole compounding and curing process is done with great accuracy to create a consistent product leaving the factory followed by a completely inaccurate scrubbing (post cure) procedure.

Brian

[Mark Filip]

I have had much better sucess this year with the tires lasting much longer. This year I spoke with someone at Hoosier and he told me to just make sure I scrub them while bringing them slowly up to temp without overheating them then letting them sit for at least 24 hours but up to 2 weeks is best. I did that with great caution this year and the tires have been great 1 set I have 11 cycles on them and the other I have 2 so far. I will run the 11 cycle tires as far as I can on the next test day so that should put them around 15. I have gotten quicker but I do not think that has anything to do with the tires but they still feel pretty good at 11 and my times have 2 cycle tires feel pretty much the same. I ran same tire pressures as I did last year and the year before and last year I did scub tires but I think I may have overheated them the first time and they were a bag of crap. I will know more after my next event.

Also wanted to add I flip tires between each weekend

[smsazzy]

Why no Master Thesis or Doctoral Dissertation on some aspect of the subject?

"...perhaps the exact temperature is not given because it is unimportant." It does not strike you as odd that the whole compounding and curing process is done with great accuracy to create a consistent product leaving the factory followed by a completely inaccurate scrubbing (post cure) procedure.

Brian

We have already established that Pro teams don't reuse tires, right? I would think it logical that anyone who would write a thesis on racing tires would more than likely be looking to be employed by a Pro team. Therefore it would be logical for them to write on a topic actually applicable to their future employers. If I wanted to go get an engineering job at Ford, I wouldn't write my thesis on submarines.

As for the second question, no. It does not seem odd. In fact, it makes perfect sense given that different chassis, different classes and different compounds of the same tire all perform at a different optimum temperature. Perhaps more important than an exact 187 degree scrub temperature is to scrub the tire in the operating temperature range. Which is why all scrubbing instructions say to gradually work up to a speed that is within a few tenths of the normal lap time without sliding the tire.

It is also perfectly plausible that you only need to cross a certain temperature threshold to break those bonds. There is another process known as boiling water that is similar. Once you reach 100C, water is boiled. You don't have to boil it for a duration of time to consider it boiled.

[Wren]

You stating something is science without any actual research proving that it is valid science. I have studied this subject and not found any science remotely backing up your statements. You should be ignored until you can validate you statements.

This is very similar to the state of the current criminal justice system where it has been determined that DNA is the the only scientifically valid form of forensic evidence. As an example all the non-DNA forensic work the FBI does lacks any scientific credibility. The same thing is going on with the subject of tire scrubbing even from the tire engineers. So Tire Rack charges $15 for some activity, does that validate it scientifically?

None of this would be hard to document in a highly controlled test, so why no published reports. Why no Master Thesis or Doctoral Dissertation on some aspect of the subject?

There is certainly research out there on the topic, supporting the concept of a tire changing properties after "breaking in."

Start with the FSAE tire test consortium.

It is also not accidental that the manufacturers also encourage this behaviour.

[Hardingfv32]

There is certainly research out there on the topic, supporting the concept of a tire changing properties after "breaking in."

Start with the FSAE tire test consortium.

It is also not accidental that the manufacturers also encourage this behaviour.

I am familiar with with the FSAE tire test consortium. Their test procedure does cycle a new tire through slip angle sweeps before testing a new tire. From the report:

"Another “parameter” that is very important in tire testing
is the technique used to warm-up and condition a new
tire before implementing the test matrix. A brand new
“sticker” tire does not have the same force and moment
characteristics as a tire that has seen some use. The
initial break-in of a new tire serves to bring the tire up to
temperature as well as work the tire such that the
internal molecular cross-links and various plies rearrange
themselves into their “used” condition. This break-in is
the final major step in the curing of the tire, and it needs
to be completed before data relevant to the long-term
use of the tire can be collected."

The report makes no implication that the tire is better off after this break-in process, only that the test matrix data will be different after the break-in.

There is no research indicating that changing the molecular cross-links and rearranging plies is of any benefit.

If the break-in process is so important why is it not a offered by the tire manufactures at least on some of their products?

Brian

[Wren]

The report makes no implication that the tire is better off after this break-in process, only that the test matrix data will be different after the break-in.

There is no research indicating that changing the molecular cross-links and rearranging plies is of any benefit.

Seriously? Just a few posts up you say that you haven't seen a paper describing smsazzy's comments regarding tire chemistry changing after break in, then you say you are familiar with the FSAE TTC that describes tire chemistry changing after break in.

The tire changes after break in, I guess we can agree on that. Since we have agreed on that, then the next step would be to listen to the manufacturers and the people using the tires. Hoosier certainly says that a scuff will extend the life of their tires and racers seem to have the anecdotal evidence to back it up.

If the break-in process is so important why is it not a offered by the tire manufactures at least on some of their products?

Brian

I doubt this is a serious question, but I will give you a serious answer. My understanding is that the mold compound serves another important part in the shelf life of a tire. I am told that it slows the "outgassing" of the tire. If the manufacturer was to offer the scuffing process, they would limit the shelf life of the tire. Instead they describe a scuffing process to use for increased longevity.

[budawe]

Wyztek, sorry about the thread being over run by keyboard commandos, but in response to your specific question, yes, set up can, and usually does, change with brands of tire. As a matter of fact, set up can change from set to set within the same brand. Ever hear a TV interview where the person says they got a "bad" set of tires? Most race tires are hand made and will vary from set to set. Depending on how narrow the sweet spot is for a given car, changes will likely be required. Tracks really change over the span of a weekend with oil and rubber build up and loss of grip. That will require changes to set up to "chase the track." Set up is a moving target and no two sessions will be identical.

I find that keeping notes and having a baseline really helps. I align my car every weekend and check shock pressures. I start with my baseline alignment and check my notes from a previous weekend at that track. There's enough variables out there, don't let the car become one as well. Hope this helps and answers your questions.

[grapefarmeral]

http://www.tyre-technology.com/index.php/home

[Hardingfv32]

Seriously? Just a few posts up you say that you haven't seen a paper describing smsazzy's comments regarding tire chemistry changing after break in, then you say you are familiar with the FSAE TTC that describes tire chemistry changing after break in.

The tire changes after break in, I guess we can agree on that. Since we have agreed on that, then the next step would be to listen to the manufacturers and the people using the tires. Hoosier certainly says that a scuff will extend the life of their tires and racers seem to have the anecdotal evidence to back it up.



I doubt this is a serious question, but I will give you a serious answer. My understanding is that the mold compound serves another important part in the shelf life of a tire. I am told that it slows the "outgassing" of the tire. If the manufacturer was to offer the scuffing process, they would limit the shelf life of the tire. Instead they describe a scuffing process to use for increased longevity.

Had the FSAE paper but had not noted the single paragraph on break-in. It was filed under test data as the main object of the paper. Spotted the information during a search last night.

Back to the criminal legal system for an analogy: After years of believing in a invalid forensic science system, most current judges and lawyers still have a had time not accepting this non-scientific forensic evidence. It just all fit so nicely in place, it just made sense. Some of it was even developed by the great FBI. Now a scientific study has demonstrated that all is not what it seems in the world of forensic evidence. The FBI never did one scientific study to backup their evidence analysis.

The same could apply to what the tire manufactures are telling us about tire scuffing. The FSAE paper notes the special rolling floor test machine that could provide such data. So why are no reports available? Why are there not ideal 'scuffing' procedures for us to attempt to use? Anecdotal evidence is completely useless in this case.

If scuffing extend tire life, why is it not used in F1 where tire life is a major issue these days? I still say the manufactures would provide the service if it was of benefit. I have never heard of any such service at even the highest levels of motor racing. As far as resealing the new tire after scuffing, why not just reapply the mold release? If out gassing is an real issue why are tires not seal in plastic before shipment?

Brian

[Tiago Santos]