Rotary Car Club - Drifting, hellaflush, slammed, tire stretch blog/bash thread.

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- Drifting (https://rotarycarclub.com/forumdisplay.php?f=251)

- - Drifting, hellaflush, slammed, tire stretch blog/bash thread. (https://rotarycarclub.com/showthread.php?t=13015)

Quote:

Originally Posted by sofaking (Post 135576)

The part I don't think you guys are understanding is the difference between theory and fact. You're talking in theory, not fact. I'm talking in experience, not fact. I understand that all I can tell you is my experience, and that the only testing is seat of the pants and lack of problems. I agree this doesn't prove anything other than that I haven't experienced problems from the setup.

Let me help you better understand:
Fact
Theory
Material Science

Material Science is not theory (in fact do a word search for 'theory' within that article).

Quote:

What I want from either of you is PROOF not theory. Which I don't think you can provide. I.E. even if I test with your technique of stretching the tire and driving around, then doing the same with a non-stretched tire (which isn't a bad idea). I don't have a way to test that the sidewall is:
1) weaker than it was previously
2) weaker than the non-stretched tire after the same miles
3) the strength of the tire is negatively effected enough that it's not strong enough to hold (or degrades at X rate and will not be strong enough to hold after X miles).

Measuring the plastic deformation automatically ensures weakness is present in the polymer. That's the nature of the beast. That's fact. If you wish to argue it I can freely back up that claim.

Quote:

I'm not arguing for the sake of arguing, I'm offering you the opportunity to prove me wrong. I admitted I was wrong when you showed that the wheels were 10" wide in my video. I'm not sure if you want me to jump on one foot in circles or something to make sure it's sincere, but I am willing to admit I'm wrong if proven.

You're arguing from a false presumption. Feel free to question what I provide, but you better be able to support your question with sound understanding of the mechanics of the materials in question.

Quote:

YOU ARE TALKING IN THEORY.

See above. It's not theory. In fact I can get you values of various materials for you. Point in fact check out this website for more information on what material science provides:
Matweb

Quote:

I'm not saying that you can't be right. I'm saying if you want me to admit it, you have to prove it. Otherwise admit you're talking in theory, and you believe your theory is sound. Because that's what's currently happening. Science is theory until proven.

I guess I can hang up all understanding of how materials works. I mean, how materials deform and work under load just is theory and not knowledge or application of the theory in question. I mean surely I couldn't get the yield and ultimate stress for the materials with a science... oh wait.

If you want me to take you seriously you might want to back away from what you're attempting to do as you will fail miserably.

Quote:

An acceptable answer could be as simple as an equation taking into account a given car weight (take an FC), a given tire (pick one that you can find data on), all the forces in question acting on the tire (stretch 215/40-17 on 9.5" wheel, load, pressure, etc.) and tell me how long a given tire will take to explode, deform to failure, break bead, whatever your premise that's supposed to happen.

Would you also like me to use a Monte Carlo simulation to ensure I capture 99% of all possible mileage outcomes across all proprietary tire compounds--Give me a break, I'm not going to waste my time doing that. I know how the rubber is going to react and have asked people who have worked for tire companies and I have yet to find a single individual who would endorse or recommend doing such.

Quote:

Then do the same math on a non-stretched tire and see if it should fail farther out, and if so how much farther. This would still be theory because it hasn't been tested but if you want to do this without making up numbers that would be a reasonable argument. I personally know I'm not good enough at math to be able to be accurate (mainly the math about the plastic and elastic sections and force exerted on them). I would venture to guess that the rate of the non-stretched tire is WAY beyond the warrantee of the tread life, and the stretched tire would probably be less, but I'd guess still tens of thousands of miles (guess based on experience).

So what you're saying is that you're willing to sacrifice factors of safety for deforming a tire and putting strain on the shoulder that is not normally there. Thereby negating entirely the built in factors of safety which the company determined prior to construction. (Just so you know, this is fact. It is standard operating procedure for any engineering done within any field).

Quote:

Short version: Admit you're talking in theory or post data. Actual numbers of when the tire will fail.

Admit you have no idea what you're talking about at all and read what material science is and does. It's not theory.

Quote:

Originally Posted by sofaking (Post 135578)

Yes, the tire will fail, all tires fail. Tires are designed to fail. But if the estimated point of failure is 60,000 miles... then it's not really a problem. If the estimated point of failure is 10,000 miles... then obviously it is a problem. Meanwhile arguing with no facts about the science of it besides making it "weaker" doesn't prove anything.

Weakening a tire in any respect is not a good thing. Would you be willing to drive on a tire that has a weakness in the binding agent between the tread and sidewall?

I mean, sure what could 1% hurt

Quote:

1% weaker is nothing, 500% weaker is huge. No numbers are being discussed. If you break a leg after it heals it may be "weaker" but it's still going to last you your whole life.

Broken legs, once healed, are actually stronger than they were before they broke. Tires are another matter, so why discuss it?

Additionally how are you going to determine 'weaker'? Are you talking yield (which is the limit before plastic deformation occurs) or ultimate (catastrophic failure)? From matweb posted above Butyl Rubber has an Ultimate Tensile stress of 17.0 MPa. Preloading the sidewalls to an unknown state of stress reduces the amount of elastic region available, loading until the ultimate stress in a corner could be possible depending on the amount of preload and the lateral force applied.

Quote:

If you hit a home run with a wood baseball bat it will be "weaker" but it doesn't mean it doesn't have 500 more home runs in it.

Neither here nor there in this discussion.

Quote:

More and less are simple concepts to define larger or smaller amounts. To not define the degree of more and less is useless to argue. Can I have more coffee please? 3 drops is more, an overflowing cup is more. Obviously in that case you just want the cup topped off, but its a pre-determined amount that the person pouring assumes based on experience. If you only want a half a cup you have to specify that amount. We're not talking about amounts, we're talking about more or less.

Unfortunately we're dealing with engineering and tires, not coffee. Keep it on point or stop talking. Your choice.

Quote:

If that's the case, with my understanding of physics I can say... Yes, I believe you're right. The tire will last less time than would be possible without stretching. But do I agree it's unsafe, or won't last the life of the tread? No.

To what are you referring in physics? More to the point; how much stress are you putting the sidewalls under and what cornering loads are nominal for the tire? When you stretch you remove the ability for the 100's of hours put into development to be applied correctly. You could have 50,000 miles on a stretched tire, or you could have 0.001 miles on a stretched tire. The issue is you alter the geometry of the wheel to the point where weight, friction, heat, cornering loads, and manufacturing defect are all applied differently than what was tested.

Quote:

I'm not trying to be a dick at this point. I'm not attacking either of you, I'm merely clarifying in different ways to see if you can understand what I'm saying. Sometimes when talking to people it requires explaining in different ways what you're trying to convey. I'm not belittling, I'm merely trying to get you to look at the argument from the other side using real world examples.

And I'm using proven and applied science to show you why it's not a good idea.

What's this, I don't even...

I'll put my 2 cents in after scanning through all the posts..

Start off, I'm no expert.. But though out my years of reading and trying out different tires, I do have some sense of it all.

My opinion about general thoughts on tires... Size, compound, suspension set up, wheels, etc makes your car handle totally different.. At the end, I believe in what your thoughts on how the car handles.. In order to achieve this, you really need to try out different set up (Hence at one point, I had 14 SSR comps with different size tires and different width wheels... and sometimes different compound tires).

My definition of "stretching" is going beyond the recommended wheel width by tire companies. Of course their recommendation is generalized so, I would say way beyond what they recommend is what I call "stretching".

Example...

255/35/18 that I run on 10 inch wide wheel could be considered by some as stretched.. but I don't as its the max rim width by tire companies. But to run 235/35/18s on 10, I say that's stretched.

But I do have to admit, Its more for looks than ideal set up for track nor for street driving. I'm sure you all know, stretched look require higher tire pressure and is more likely to loose bead if tires impact. The later part is not fiction but fact! If you stretch the tires so much and you accidentally hit something hard, there is much higher chance for the tires to loose bead. For me, that's not worth risking your life for gaining some special look.

That being said, If you understand all this and want to do what you want to do, than I have no issue with it. But stretching the tires and not knowing the negative affects and then recommending to newbs or others, I think that's wrong.

Another negative effects of stretching I see is looking contact area of tires. For front, some prefer because it rounds the tires and some say they prefer running smaller tires for width of the rim. But running stretched on back, I think it might be good for drifters but not sure about track guys or drag guys :)

Anyhow, most what I said, I know all of you know.. so just me rambling on.

Quote:

I didn't have an opportunity to respond before the thread was edited to remove anything that was said. I glanced at your response but didn't have a computer handy to respond or look at your links.

I'd be glad to look at the links you posted if you want to forward them. I'm seriously not just trying to piss you off, you seem like an intelligent guy... Your argument is just lacking detail in "real world" application.

There again attempting to say that what I'm stating is outside the realm of applied science. Look at the links. This is applied science. This is real world.

Quote:

You aren't willing to bend in the argument at all even to see my perspective, on the other hand I have adjusted my statements to clarify what I'm looking for and you're still shutting me down seemingly without really reading what I'm saying and focusing more on each sentence as it's own argument.

Because that's how you read. Line upon line, sentence upon sentence.

Quote:

Please slow down and read what I'm saying, I really would like this to be clarified (be it in front of the forum or not).

I've never been a "follow the rules" kind of guy. From my experience in the world I find most things are over-engineered if they're mass produced and can cause death in the hands of the general public.

From this stance alone you have really no understanding of how mechanics works do you?

Quote:

In my experience tires are manufactured so that the sidewall holds up LONG after the tread is gone. In some cases 4 times longer.

http://www.p2pays.org/ref/11/10504/html/usa/retread.htm

Retreading reuseses the sidewall for 3 to 4 times before it's weak enough to justify replacement. At that rate even if a stretched sidewall lasts 50% less time it would still "safe" because it will outlast the tread.

See above picture. Does it look like that sidewall lasted 50% as long as normal tire?

Quote:

If you can show me how this dramatically effects the tire (in a real world application way) I'll stop using stretched tires. I'm not unreasonable, and I'm not saying the science you're using is bad, wrong, or anything else. I agree that the concepts you're talking about are sound.

I'd hope so considering that it's how the tire company does it. Whether or not you continue to kick against the pricks is your call.

Quote:

That doesn't show me how badly this negatively effects the tire. Based on information I have the negative effects would have to go over 50% decreased life to pose a threat of danger. If you're unable to do the math just say that and we will move on. You have repeatedly asked me for specifics and offered to clarify and they threw it in my face when I clarified or asked for specifics.

Such as what? I answered everything you posed to me to my knowledge. I've told you I'm not going to do the math as it's a waste of my time. You're free to do whatever you want.

Quote:

If you're in the same boat as me (or anyone else on the forum for that matter) and don't feel confident in your math then just say that and we can move on. But your implying that you can do it, and from the informed argument you're making I think it's possible you might be able. I don't care if you throw some constants in to make it easier. I.E. loading the tire at 1g lateral for the life of the tire, or whatever. I just wanted some sort of math to back up the theory even if it's only a guestimation. Currently I've got nothing.

So in other words what you're asking for is some sort of math that you aren't sure you will understand or know if it is accurate or if it even reflects reality. Which begs the question; why?

Physics - the science that deals with matter, energy, motion, and force.

So then that means

Physics = Theory
and thus is now ruled an irrelevant topic in this discussion. :lol:

So I just read through this whole thread.

And I 100% understand why no one takes drifting serious now. I am so sad.

Something along the lines of a select few ruin it for the rest?

that tire (probably) died from underinflation. seen plenty of those pics

heres the firestone report
http://www.ce.berkeley.edu/~sanjay/R...WEB_Secure.PDF

couple snippets from the first page:

Quote:

...there are no well
established criteria for in-service tire failures against which tire components
are designed.

Quote:

...while
one can and does perform many standard laboratory tests on tires and their
components it is not clear how these are related to in-service failures.

not looking so good for "this is fact, not theory"

I have a few of these Emails from different tire manufactures.
Thank you for contacting Michelin
Monday, December 27, 2010 7:06 PM
From:
"Michelin Consumer Care" <conrel.en@michelin.epowercenterdirect.com>
Add sender to Contacts
To:
rotordad@yahoo.com

December 27, 2010

Hello Chris,

Thank you for your email. We welcome the opportunity to serve you.

Mounting a tire on the incorrect size rim could be dangerous and a safety issue. We strongly discourage it.

While there is nothing on our website at this time related to mounting tires on the incorrect rim size, we would be more than happy to answer any questions you may have if you call us at the number listed below.

We appreciate your business.

Please call us at 1-800-642-4354 (toll free) between 8:00AM and 8:00PM Eastern Time Monday through Friday or between 8:30AM and 4:30PM Eastern Time on Saturday.

Sincerely,

Sherry Cooper

Consumer Care Department
Certified Michelin Product Expert

PS: It's important that you get all the safety-related materials that come with the purchase of new Michelin passenger and light truck tires. If you did not receive a warranty book, you can download one at www.michelinman.com/warranty/. If you did not register your tires, please take a moment to do so at www.michelinman.com. Registering your tires is easy and takes just a minute.

Participate in our survey to become eligible to win a Michelin Man bobble head doll! A random drawing will take place at the end of each month. The winner will be contacted via e-mail to verify the shipping address.

Paste the line below into your browser:

http://www.asurvey.net/michelin/?2587883.85688.59

Privacy Policy - http://www.michelinman.com/privacy/

(Please include the line below if you reply to this email.)

http://us.mc574.mail.yahoo.com/mc/we...jsrand=8398002
Case number: 2587883

yah thats the same blanket statement seen on all the tire manufacturer's websites. what people want to see is something empirical. ie, not just a CYA policy

Well I sent them an email directly about tire stretching, if you don't like the response they gave call the number provided to get a better idea. I am willing to bet they have more experience & have betters ways to test then any of us. No need to dance around the issue, just because you can make something fit doesn't mean it's right. If it is suggested by the tire companies not to mount tires on wheels outside their recommendations there must be a reason. You say people want to see something more specific, that's fine I understand. Now on the other hand how about this? Where is the proof of the opposite, since it all seems to be the non stretched tire guys providing some sort of info.

i guess proof of the opposite is the lack of failure. no one has yet to find any account of a tire failing due to stretch. there are a few scattered failures, but most are due to underinflation, hitting potholes, or otherwise undetermined. if it is in fact an issue, there should be evidence of it in drifting. if a stretched tire is going to fail due to the stretch, that seems like the most likely venue

also should be noted that the burden of proof is on the dont-stretch side. evidence for something not happening is infinite.

My contribution to this thread.

If you really think tyre stretching is a good thing then

You're a fucking idiot.

It also looks bad.

Enjoy!

Also found this linked on another forum

And perhaps one should contact their insurance provider and ask them if a claim would still be valid when they find stretched tyres after you prang your car?

http://www.aus300zx.com/forum/showthread.php?t=290328