Drifting, hellaflush, slammed, tire stretch blog/bash thread.

[vex]

Starting early are we, lets see if you address any of the points I've raised thus far.

(for review)

And completely negates the speed rating of the tire. Sidewall deformation caused by stretching not only results in premature tire failure, but also eliminates the speed rating as viable metric to ensure safety of the car.

Stretching the tire really has no benefit beyond aesthetics (but last I checked cars were meant to be driven).

On the contrary, see the above quotes from installers and individuals in the business. Even if they tell you it's bad and you insist upon it being mounted, and a family dies because you used your predictable vehicle behavior to slam into them, who's going to take the heat for all those who died? You? Or are you going to let the buck go to the individual that broke the law in mounting your tire?

Do you really want me to get the information I already posted from a tire designer to prove you have altered the tire dynamics to no benefit?

Just out of curiousity as the geometry is deformed, tire pressure is altered (maximum tire pressure--do you still put in the recommended amount, are you eyeballing it, or some other means outside of manufacturers spec)?--With due respect, you answered this by stating you eyeballed it.

Furthermore stretching tires can run aground upon other design features such as Michelin's Stress Equilibrium Casings

What do you mean by technical data? How much tire defelction is altered during a specific corner? Would you like it arranged by contact patch size, wheel size, or some other metric? You seem to demand specifics but be purpously obtuse when it comes to defining the metrics.

Would you like to see acceleration data, lap times, or some other metric? If you have an idea of what you want, I'm sure I can hunt it down for everyone to see. Beyond what I have already posted, what specifically do you have issue with? Is something stated that is not accurate or correct? If so, what is it and why?

Then you dictated that I was belittling you. In all honesty I'm still waiting on those answers from page 3. Care to elaborate?

back to that list:

What data do you want? Do you want the proper PSI for tire inflation with modified geometry, or would you like something else?

Actually I have never heard of a properly mounted and inflated tire ever breaking the bead without a structural defect manifesting itself. But since this is your allegation, find me a documented incident where one such occurred.

Which begs the question, how do you gage proper inflation when you deform the sidewall that much? You do not fill it to factory spec. What metric do you use to fill it or are you just filling it 'till it's "that'll do?" For all you have shown, you could be driving with it under inflated or over inflated and you wouldn't know would you? You're guessing on something that you have no data on. If you have data on proper pressure filling on deformed sidewall tires then I suggest you enlighten us on how the tensile strength of the sidewall is accounted for.

The list goes on and on, but you have yet to address those, so I'll leave it there for now.

Originally Posted by sofaking

This was my argument all along. Your conveluted subject changes and misdirection while pulling apart each sentence without reading the point of the post is what caused the argument. Notice how the original posts say that it WILL lead to failure (certainty) and this one said it CAN lead to failure (possibility).

Are you telling me there's tires that will not fail? Obviously not, so it still stands that all tires fail (certainty), as you have stated stretching a tire decreases the time or life of the failure, no? So back to what I said originally; Stretching a tire beyond manufacturers spec can and will cause it to fail. Do you know when or for that matter, if you're encroaching upon the plastic region of deformation of the compound? I've given you a simple test to verify if your specific stretch does, but you refuse to run the simple test that will give you the answer you're looking for. That's your issue. Not ours.

Without the math niether of us can be certain.

Actually, you don't need math to be certain. You need to understand the science to be certain, otherwise you will always wonder: "Did he just BS me, or did he just pull some number from somewhere?" So in all honesty would you be certain?

But if it doesn't lead to failure I'm not sure how it's reasonable to argue it's unsafe.The failure rate of anything is 100% on a long enough timeline.

Thank you for agreeing with me. Is a stretched tire going to fail before or after a properly mounted tire if they undergo the same driving conditions? How about if they hit a pot hole at speed, will they both have the same lifetime?

If we don't define when its going to happen then to argue the safety of it is pointless.

Yes because you don't know when you're going to crash into a wall during a circuit so lets not worry about safety. I mean, seat belts, harnesses , helmets, barriers, they don't stop failure or for that matter know when failure will occur we must not need them. Again, logical fallacy to argue this point.

Also for clarification, the whole science arguement that started wasn't by me. You felt the need to justify what you were saying by trying to bury me in science that I clearly didn't go to school for. I understand basic concepts of physics and how they apply in the world.

Oh... you didn't say:

You're dealing with concepts not application, that's theory.

What we've been discussing, and have been for ages is Material Science (which is an applied science, not theoretical). Your statements have been to the effect that unless I generate some random number everything I'm attempting to show you in science is just theory. Unfortunately I'm not that gullible, nor are a majority of the individuals on this board. Now continuing with your post...

I never argued that you weren't scientifically acurate to say that it's weaker, I only argued that nothing definitive about the safety concerns can be determined from the information except the single thing defined (weakness).

Do you remember that little post about elastic and plastic deformation? By weaker, it means you have removed tensile strength from the tire. This translates to a closer proximity on the stress-strain curve to the yield (where plastic deformation begins), and thereby closer to the ultimate yield (where you have catastrophic failure). More to the point, as soon as you encroach upon the plastic region the tire is considered failed (in polymers it's whenever necking occurs in a test sample). Hence, weaker is not some arbitrary term you seem to think it is. It is scientific. It has value.

I don't feel a need to continue with you picking apart every word I say, but I would like some clarification in acceleration not being a force.

Be happy to oblige.

Acceleration changes the tire speed in relation to the ground, the direction of the tire (from a stop), and the shape of the tire through centrifugal force and friction with the pavement. Can you clarify why acceleration would not be a force?

Acceleration, by itself, is not a force. If you look at the units of acceleration they are in terms of length per second per second (or second squared). Inertial forces can be derived by using acceleration, but must by definition be coupled with mass.

I'm sure you would break it down into different factors of acceleration, but as a broader term why would it not be right?

Lets look at a very simple problem. Take a particle of finite mass traveling through space at a constant velocity (a=0). We now wish that particle to travel in some other direction. We therefore impart a force upon the body. At time=0 acceleration is still naught, though the force is applied, the change in direction has not occurred. As time progresses acceleration increases so long as that force is still applied (or in otherwords you have a constant force [lbs] causing an increase in acceleration [ft/s^2] over time)

It doesn't look as simple as placing it in Newton's second law because there are variables to rotation, but it still seems to apply to the description.

Acceleration is a derivative (as in derived from, not the mathematical operation, though it is that as well) of the forces. For instance; you will not apply an acceleration to a tire to get it to move. You can understand that the tire is accelerating, but the acceleration itself is not the cause. Using one of the previously discussed terms torque; the tire has a torque acting on the center of the hub. In other words you have a force acting through a moment arm which is then resulted into the tires acceleration.

I would think that if acceleration isn't a force then braking (the removal of rotation) would not be a force.

If you were using braking as a form of acceleration it would fall under the same as acceleration. I was personally using braking as another metric of force being applied to the brakes via friction which would impart a torque on the hub.

Can you clarify please with a concise thought instead of breaking down each sentence?

Nope. But hopefully that helped.

[sofaking]

I don't feel the need to address a whole bunch of questions directed at a point I wasn't trying to make. I'll answer some though, I find that 1/2 of them are phrased in a sarcastic or rediculous nature because they're asking about things that were clarified in the topic already. The point wasn't if you could give me a million tests and contribute the rest of your life to the concern about tire safety. I was merely stating without said information which niether of us have, we can't determine a whole lot.

As for gauging proper inflation I concede, I don't know how to determine what it should be set at without feeling it out. I addressed that I fill them to 40psi, but I'm not sure what you want there. If you have an answer do share, if not... the question doesn't appear to have a point but to discredit my scientific process for determining proper tire inflation levels which I'm sure would also require math to determine anything specific.

I will offer a link to a tire that de-beaded for no apparent reason (or possibly someone deflated it). The thing is nothing can be proven in that field either without knowing 100% what all the variables are. I have personally had it happen for seemingly no reason... obviously there is a reason, but I don't know it so it's unexplained.
http://answers.yahoo.com/question/in...4221537AA4wUoh
Someone previously in this same topic even mentioned they've seen properly mounted tires debead if I remember correctly.

I did state that I believe you're arguing theory, I don't retract that. But I will happily clarify what I'm refering to. It's not the science you're quoting that I am calling theory. I'm arguing that the conclusion you've come to about the safety is your theory, your opinion, your conclusion. I made a graph to illustrate my point. I never said that your information on tire deformation was wrong or theory. I argued your conclusion of safety concern is jumping to a conclusion from the science and that's the part I wanted proven. Obviously when you change the shape of a material that was designed for a certain shape it will stress or break it. That's common knowledge.


To state where on this graph you should plot a point of stretched sidewall failure would be only theory, speculation, guessing, whatever you care to call it without a pile of math that niether of us want to do, and only one of us knows the formulas (hint: not me).

As for your diagram...

Is this what you want? teach away.

[vex]

Originally Posted by sofaking

I don't feel the need to address a whole bunch of questions directed at a point I wasn't trying to make. I'll answer some though, I find that 1/2 of them are phrased in a sarcastic or rediculous nature because they're asking about things that were clarified in the topic already. The point wasn't if you could give me a million tests and contribute the rest of your life to the concern about tire safety. I was merely stating without said information which niether of us have, we can't determine a whole lot.

I haven't seen 'em answered but if you have a post number to refer me to I'll gladly re-read them.

As for gauging proper inflation I concede, I don't know how to determine what it should be set at without feeling it out. I addressed that I fill them to 40psi, but I'm not sure what you want there. If you have an answer do share, if not... the question doesn't appear to have a point but to discredit my scientific process for determining proper tire inflation levels which I'm sure would also require math to determine anything specific.

Unfortunately what you describe isn't scientific. Tensile side wall strength is compromised with stretch.

I will offer a link to a tire that de-beaded for no apparent reason (or possibly someone deflated it). The thing is nothing can be proven in that field either without knowing 100% what all the variables are. I have personally had it happen for seemingly no reason... obviously there is a reason, but I don't know it so it's unexplained.
http://answers.yahoo.com/question/in...4221537AA4wUoh
Someone previously in this same topic even mentioned they've seen properly mounted tires debead if I remember correctly.

During normal driving conditions?

I did state that I believe you're arguing theory, I don't retract that. But I will happily clarify what I'm refering to. It's not the science you're quoting that I am calling theory. I'm arguing that the conclusion you've come to about the safety is your theory, your opinion, your conclusion. I made a graph to illustrate my point. I never said that your information on tire deformation was wrong or theory. I argued your conclusion of safety concern is jumping to a conclusion from the science and that's the part I wanted proven. Obviously when you change the shape of a material that was designed for a certain shape it will stress or break it. That's common knowledge.

Lets link two ideas here. Since you do not know how much air would be required to fill tire properly you do not know how the tire will be stressed. Underinflation will result in the previously posted picture. Overinflation will result in a blow out during normal operation. Couple that with the alteration in the geometry you now have points of stress along the tread and shoulder. The issue of a stretched tire can then be split to different points:

1. Failure due to underinflation or overinflation
2. Failure due to sidewall failure
3. Failure due to tread separation

Tensile strength of the sidewall affects the first two points. Since we're altering the geometry of the tire when it's stretched we can know by your own admission that:

Obviously when you change the shape of a material that was designed for a certain shape it will stress or break it

Thereby removing factors of safety.

To state where on this graph you should plot a point of stretched sidewall failure would be only theory, speculation, guessing, whatever you care to call it without a pile of math that niether of us want to do, and only one of us knows the formulas (hint: not me).

And I'm attempting to get you to understand the math so I'm not wasting my time. Additionally what tire would are you desiring?

As for your diagram...

Is this what you want? teach away.

Your forces are off. Displaced air is not needed and can be removed (unless we have lighter molecules than air). You're also missing a normal force (acts perpendicular to the tire) that keeps the tire from pushing through the ground.

[TitaniumTT]

That is all

[EJayCe996]

Originally Posted by TitaniumTT

That is all

oh yes, we hooked a smartphone up to someone's car audio back in Cali and blasted this when we pulled up next to Glenn on the street

[sofaking]

For the sake of moving this along...

[mazpower]

Originally Posted by EJayCe996

oh yes, we hooked a smartphone up to someone's car audio back in Cali and blasted this when we pulled up next to Glenn on the street

Still not as bad as hearing my own balls slap and watching it on a big screen in a Vegas casino bar the night before my wedding. The people's reaction was classic once they figured out what the noise was.

[sofaking]

Originally Posted by vex

I haven't seen 'em answered but if you have a post number to refer me to I'll gladly re-read them.

I don't feel like going back and quoting, but everytime you asked for information about what I would like it was completely sarcastic and ended with you telling me that you didn't want to do the math. I got as specific as I was looking for and told you that you could use constants for variables if it made it easier. Your response was that you didn't want to waste your time. So quoting myself getting told that you aren't going to do it doesn't help. Move on to the physics lesson if you'd like to make a point, it's the closest thing to figuring anything out we've gotten to.

Originally Posted by vex

Unfortunately what you describe isn't scientific. Tensile side wall strength is compromised with stretch.

I already said that was your point... so if you're not adding anything what is the point in saying it again?

Originally Posted by vex

Thereby removing factors of safety.

So you're saying that there is no possibility that the tire can sustain this, or you're just saying that you know a lot of factors determine the safety of a tire and without the math you can't do anything but speculate what may or may not happen?

Lets define for the sake of discussion that safety is the tire not failing (in any way) before the tread is used up during normal driving conditions. I understand it doesn't meet the original specifications, but the only information we know as of yet is that it will fail to the left side of my graph. Whether it gets even close to the green area is complete speculation.

Originally Posted by vex

Additionally what tire would are you desiring?

I'm using a Falken Azenis RT615k 215/40-17 on a 17x9.5 wheel.

Originally Posted by vex

Your forces are off. Displaced air is not needed and can be removed (unless we have lighter molecules than air). You're also missing a normal force (acts perpendicular to the tire) that keeps the tire from pushing through the ground.

This was the point I was making about drawing the diagram and getting to the point. Going back and forth to prove you know where you're going with your point is a waste of both of our time.

[vex]

Sorry didn't see this until just now.

Originally Posted by sofaking

I don't feel like going back and quoting, but everytime you asked for information about what I would like it was completely sarcastic and ended with you telling me that you didn't want to do the math. I got as specific as I was looking for and told you that you could use constants for variables if it made it easier.

Using variables in this sort of math will cause you to get a bunch of variables in equations that do not make much sense. We'll use constants sure enough, but leaving variables into the equations of question is going to be worse than just using real values.

Your response was that you didn't want to waste your time. So quoting myself getting told that you aren't going to do it doesn't help. Move on to the physics lesson if you'd like to make a point, it's the closest thing to figuring anything out we've gotten to.

This isn't physics in the true sense of the word (at least not from when I took those classes). This is basic material science.

I already said that was your point... so if you're not adding anything what is the point in saying it again?

It seemed to me that you were attempting to sustain this as scientific procedure. If you're no longer sustaining that or if I misinterpreted that from your post then by all means the point is moot now.

So you're saying that there is no possibility that the tire can sustain this, or you're just saying that you know a lot of factors determine the safety of a tire and without the math you can't do anything but speculate what may or may not happen?

This may better help you understand: Factor of Safety. A reduction in the FOS reduces the ability for the tire to handle the same stresses as a properly mounted tire would otherwise be able to endure.

Lets define for the sake of discussion that safety is the tire not failing (in any way) before the tread is used up during normal driving conditions. I understand it doesn't meet the original specifications, but the only information we know as of yet is that it will fail to the left side of my graph. Whether it gets even close to the green area is complete speculation.

I think this is a failure to communicate what FOS is.

I'm using a Falken Azenis RT615k 215/40-17 on a 17x9.5 wheel.
This was the point I was making about drawing the diagram and getting to the point. Going back and forth to prove you know where you're going with your point is a waste of both of our time.

Again, I think you miss the point. Discussing the science isn't for my benefit but yours. If you do not understand where the number comes from at the end of the day all it's going to be to you is a number--But if you understand where that number came from at the end of the day you will know and understand what the material is doing when you stretch the tire and place it under load.

[sofaking]

Since I clearly don't understand how to apply a torque to offer a direction because I thought it could be used as a force I wouldn't know how to add it. For the sake of this analysis lets say the tire is static.

I read the FoS link, interesting stuff. To my knowledge (making an assumption without taking hours of classes on the subject)... Passenger tires would have an MoS of +3 or +4 if the sidewall lasts 3-4 times longer than the predicted load, correct? Not to mention that any given tire usually isn't at its maximum load when installed on a passenger vehicle anyway (Which is what the FoS is engineered to. I.E. max inflation pressure/weight), correct?

Also the article covered a sentence on my point as well...

Many systems are purposefully built much stronger than needed for normal usage to allow for emergency situations, unexpected loads, misuse, or degradation.

This would lead me to believe that it is possible I am right. I'm not saying that it is or isn't "safe". I'm saying that it's possible that it is safe, correct? If it is possible that it is safe, then the obvious conclusion would be that it would not be a fact to call it "unsafe", correct?

[vex]

Originally Posted by sofaking

Since I clearly don't understand how to apply a torque to offer a direction because I thought it could be used as a force I wouldn't know how to add it. For the sake of this analysis lets say the tire is static.

Roger. Now lets look up the material properties for the Rubber of the tire (we'll assume some generic vulcanized rubber). We'll also assume (for simplicity) the rim is solid (IE it is going to deform orders of magnitude less than the tire).

I read the FoS link, interesting stuff. To my knowledge (making an assumption without taking hours of classes on the subject)... Passenger tires would have an MoS of +3 or +4 if the sidewall lasts 3-4 times longer than the predicted load, correct?

No. The factor of safety is calculated using yield and/or ultimate stress criteria. Sidewalls may or may not have 3 or 4, but it is completely determined via structural criteria (not life expectancy).

Not to mention that any given tire usually isn't at its maximum load when installed on a passenger vehicle anyway (Which is what the FoS is engineered to. I.E. max inflation pressure/weight), correct?

No. They're engineered to load criteria IE; cornering loads, static loads, etc. Although max inflation pressure and weight due play a roll into deciding the static loads they do not fulfill the entire criteria for the loads themselves (thermal, adhesive stress, etc factor in as well).

Also the article covered a sentence on my point as well...


This would lead me to believe that it is possible I am right. I'm not saying that it is or isn't "safe". I'm saying that it's possible that it is safe, correct?

Not really. It would be similar to say that a non-firing round from a gun will never fire, which isn't necessarily true. There is a possibility that the round may never fire, but would you risk it (if you're a gun enthusiast)?

If it is possible that it is safe, then the obvious conclusion would be that it would not be a fact to call it "unsafe", correct?

It's arguing a logical fallacy. A car with a slow leaking break master cylinder is safe until you're sucking in air on the freeway--that is to say, no. Using a product outside of engineering criteria is going to be unsafe especially with the current trends of lean manufacturing.