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Wrong direction for tire pattern on inmotion v13?


Finn Bjerke

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Edit: After a lot of back and forth here is the result of a collaboration with @Eucner 
(It is the last time ever I'll try to be helpfull by providing an illustration)

When installed as a front tire /\ the rubber deforms less when braking, more when accelerating.
When installed as a rear tire \/ the rubber deforms less when accelerating, more when braking.

IMO it makes very little difference in our use case as our brakings and accelerations are rather progressive.

image.thumb.jpeg.8862a12539525a17068bba3edca01c7a.jpeg

An approximation of the deformation, illustrating how the pattern structure is better for one direction than the other, as well as that the pattern deforme or resists on the other side of the patch awell, as a result from the pulling.

image.thumb.jpeg.49f52334268c64610d70bcf510512ec1.jpeg

image.thumb.jpeg.4412be0b54d43a136502732aeaabb12b.jpeg

(Old message bellow)

Spoiler

AFAIK neither will brake or accelerate "better" but the tire will get more wear from one of the two forces. Some people on motorbikes will swap front and back tires to even out the wear after a while. Seing we probably spend more time accelerating hard than braking hard, installation as back tire is probably best for our use case.

We can see here how one force will go parallel to the groves, spreading through rubber columns, while the opposite force is perpendicular to the groves, squishing where the rubber is thinner.

Considering our relatively low weight and progressive acceleration / braking strength, it probably doesn't really matter.

 

image.thumb.jpeg.a29cb9dfec23ca3cf7549c3cef0ef2c9.jpeg

 

Edited by null
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2 hours ago, Eucner said:

Are these wheels in the picture shown from front or back side? 

Shown from front. (updated to show it)

/\ is front tire direction.
\/ is rear tire direction.

Edited by null
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15 minutes ago, null said:

Shown from front. (updated to show it)

Thanks. The acceleration and braking force vectors are drawn on the wheel as free body forces, but they have ground force direction. Because Newton's 3rd law of motion, these forces are in opposite direction.

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49 minutes ago, Eucner said:

Thanks. The acceleration and braking force vectors are drawn on the wheel as free body forces, but they have ground force direction. Because Newton's 3rd law of motion, these forces are in opposite direction.

Yes they are opposite in the start (why I didn't start my arrows in the middle), but because material packs and pulls, the forces will spread outwards. I suppose I could have made lines starting parallel from the center and curving outward but the curvature would depend on several things and it gets complicated. As the point was to comment on what the different installation directions resulted in (different wear), my illustration was simplified to show how the forces (on the sides, since center doesn't change much whichever direction) travel either in the structurally strong (columns) direction, or the weaker (squished groves) direction.

Here is the naked picture in case you felt like doing a more nuanced and correct visual of the spreading forces.

image.thumb.jpeg.1078177105eb24c2b520c423dfdd7e26.jpeg

 

 

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41 minutes ago, null said:

Yes they are opposite in the start (why I didn't start my arrows in the middle), but because material packs and pulls, the forces will spread outwards.

That was not the problem.

image.thumb.jpeg.098b0bf3f546f9e6c3ec8ba8fccfff87.jpeg

Thanks for the photo. As seen from the front of wheel, the red arrow is acceleration ground force and green arrows are opposite forces in the tire. Their vector sum is zero (Newton's 3rd).

Your arrows are showing the displacement direction. The spring equation is F = -kx. The direction of force is opposite to the displacement.

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44 minutes ago, Eucner said:

Your arrows are showing the displacement direction

You could just have said that from the start, and I would have changed the vocabulary. I thought it was clear that this is what I ment as it is what interests us in this case.

I would have thought material displacement through pushing and pulling was a continuation / spreading of the original force, but now I will know it has a different name.

I will change the wording, just say if there is anything else that should be different on that illustration, keeping in mind that it’s point is to show what difference the installation direction makes to us.

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50 minutes ago, null said:

You could just have said that from the start

My bad. I just tried to say it multiple ways to maximize chances to get understood.

50 minutes ago, null said:

point is to show what difference the installation direction makes to us.

Yes, thank you taking this tire pattern direction question to more concrete level. For any conclusion's, we need to have correct names and directions.

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2 hours ago, Eucner said:

My bad. I just tried to say it multiple ways to maximize chances to get understood.

Yes, I didnt understand that you where saying i should change the wording, I thought you where challenging the directions of my arrows because of Newtons 3rd law. (edit: but aparently we where not talking of the same thing)

As for starting the arrows from the center I told you it was not my subject, as my point was the incidence on the tire depending of direction (the squishing) , and I would have thought people would understand that. In the center the incidence of the tire direction is close to nill. But I will update it as you seem fit if you think that is important to include the origin and the curvature.

I am reminded that everything should be stated, for example I thought it was obvious that the view was from the front: it is common to discuss tire pattern as seen from the front, as it it generally the most visible from there. The reflective tape was also white and not red like the standard color for the back of vehicules. I was wrong and should have stated it.

So, to get through with this, correct me from this draft:

1: I will replace "acceleration forces" and "braking forces" with "Displacement direction resulting from accelerating" and "Displacement direction resulting from braking".

2: I will curve the arrows so they start parallel from the center, as well as add a disclaimer that it doesnt stop after the arrow head.

3: As for arrow heads: they currently point away from the center because that is the direction the material takes relative to the entire tire. If you mean it is better to show the motion of the material relative to the contact patch, so inwards, do tell me. Or if all of this is wrong.

4: Regarding colors I have used green to show the direction where the tire is most rigid, so parallel to the groves. Red have been used to show the direction that is less rigid, because it compresses the groves going accross them. To simplify green is the better spread, red is the less optimal spread. Should this be different? 

5: I will use a single arrow for each "Displacement direction" to avoid any confusion regarding spread from origin, as well as make it on both sides so it is clear that this doesn't happen on a single side. It might even be better to make a gradient radiating from the "contact patch", but that isn't as intuitive when it comes to visualising the squishing on the groves, which is still, I believe, the only point that have any incident in our use case (and barelly so).

6: I will mention that the water flow arrow is purelly the direction the grove guides it when turning, but that surface tension and centrifugal forces are also at play.

Anything else?

Edited by null
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1 hour ago, null said:

So, to get through with this, correct me from this draft:

1: I will replace "acceleration forces" and "braking forces" with "Displacement direction resulting from accelerating" and "Displacement direction resulting from braking".

Sound good. You could also call it deformation.

1 hour ago, null said:

2: I will curve the arrows so they start parallel from the center, as well as add a disclaimer that it doesnt stop after the arrow head.

5: I will use a single arrow for each "Displacement direction" to avoid any confusion regarding spread from origin, as well as make it on both sides so it is clear that this doesn't happen on a single side. It might even be better to make a gradient radiating from the "contact patch", but that isn't as intuitive when it comes to visualising the squishing on the groves, which is still, I believe, the only point that have any incident in our use case (and barelly so).

The displacement is largest at the middle of tire and practically zero at the bead. If the arrow could start thick at the middle and get thinner to the bead?

1 hour ago, null said:

3: As for arrow heads: they currently point away from the center because that is the direction the material takes relative to the entire tire. If you mean it is better to show the motion of the material relative to the contact patch, so inwards, do tell me. Or if all of this is wrong.

Displacement/deformation arrows should point outwards and force arrows should point inwards. I think here the interest is only in the deformation.

1 hour ago, null said:

4: Regarding colors I have used green to show the direction where the tire is most rigid, so parallel to the groves. Red have been used to show the direction that is less rigid, because it compresses the groves going accross them. To simplify green is the better spread, red is the less optimal spread. Should this be different?

I don't think there is a universal standard for color usage in this application. Use what you like and let us know their meaning.

1 hour ago, null said:

6: I will mention that the water flow arrow is purelly the direction the grove guides it when turning, but that surface tension and centrifugal forces are also at play.

That's a good idea.

1 hour ago, null said:

Anything else?

Keep up good work.

Edited by Eucner
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In the meantime, for the sake of it, here is a simplified version intended to leave out as much possible confusion, and focus solely on the compression on the material due to braking or accelerating. Tell me if any wording or technicallity is wrong and I will corect it.

image.thumb.jpeg.efd056456e6a46320a82618f9e0e7227.jpeg

Edited by null
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17 minutes ago, null said:

In the meantime, for the sake of it, here is a simplified version intended to leave out as much possible confusion, and focus solely on the compression on the material due to braking or accelerating. Tell me if any wording or technicallity is wrong and I will corect it.

That's good for me. Not necessary to add into the picture, but if somebody is interested, the reason of differences in material rigidity is how they add up as springs. In green direction they are in parallel configuration. The relation of displacement and force is more linear than in red direction, where they are in series configuration and more progressive.

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1 hour ago, Eucner said:

Keep up good work.

Thanks!

I believe we might get close, try this one ( I hope the forum software havent reduced quality too much, it seems to lower resolution if file size is over so and so lately)
The text in the middle is probably too long, I should probably drop the part about the shape of the deformation.

Tiredirectionsanddeformation.thumb.jpg.8aae311ef486ee080958727f00b3166e.jpg

 

Edited by null
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3 hours ago, Eucner said:

Not necessary to add into the picture, but if somebody is interested, the reason of differences in material rigidity is how they add up as springs. In green direction they are in parallel configuration. The relation of displacement and force is more linear than in red direction, where they are in series configuration and more progressive.

Thank you for the added info, it is what i visualised without having the concepts to describe it. As a product designer I am interested in the behavior of material, but as I'm not an engineer I do a lot of "visualising" (things get reviewed by enginering later in the process).

 

Edit: While I think of it: On the opposite side of the contact patch we have pretty much the same deformation, but as a stretch (expansion?) rather than a compression. The wear difference on the tire depending direction must be very minimal, or non existent, since both happen on each opposing pattern direction (the "strong" and the "weak" structure (sorry for wording but to simplify) (each time a braking compresses the strong pattern direction, it also pulls on the weak pattern direction)). 

So if wear is pretty much equal, then the (only?) benefit is the lesser deformation as the compression direction goes into the "strong" / parrallel configuration pattern.

If you ( @Eucner ) agree with this I will change the first post to reflect this (that it is the leser deformation during a certain action that makes the difference, and not as I thought the wear) (I still believe that in our use case the difference means close to nothing, especially if we're not even piling up wear over time)

Edited by null
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9 hours ago, null said:

Edit: While I think of it: On the opposite side of the contact patch we have pretty much the same deformation, but as a stretch (expansion?) rather than a compression.

Yes, that's partly true. There is difference how rubber behaves when it is pushed against ground or pulled off. The first one has longer contact patch. The compression side can also buckle and the stretch side can't.

The rigidity of tire comes mostly from ply layers. The variation in road tires tread pattern will have much lesser effect. So, perhaps no need to dig this too deeply.

The tire wear comes from deformed rubbers slippage under the load. The wear gets exponentially bigger when slip increases.

Regarding the water flow direction, it is also important to note what happens in cornering. The front tire pattern will spread water out of the corner and rear tire pattern into the corner, which is bad because that's the way we are going.

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17 hours ago, Eucner said:

Yes, that's partly true. There is difference how rubber behaves when it is pushed against ground or pulled off. The first one has longer contact patch. The compression side can also buckle and the stretch side can't.

Yes, I did a visual to better show the deformation of the pattern and we can see a bit on the profile how the stretch side do not buckle where the compression side does a little. Not being a simulation it is not entirelly correct and do not take in consideration the structurality of the pattern, but it shows how the displacement in one case goes in the strong direstion of the pattern whereas the other one does not. (Here a 2cm displacement of the contact patch on a 80/90-14 tire, just an example to be readable)

(Most visible when flipping between the two after clicking one)

Tiredeformationstrongdirection.thumb.jpg.0b047f52adcd15bb8806b54b26c1e622.jpg

Tiredeformationweakdirection.thumb.jpg.82cd66df7ce2366130462dc157df5523.jpg

Edited by null
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On 2/9/2024 at 2:47 AM, null said:

Yes, I did a visual to better show the deformation of the pattern and we can see a bit on the profile how the stretch side do not buckle where the compression side does a little. Not being a simulation it is not entirelly correct and do not take in consideration the structurality of the pattern, but it shows how the displacement in one case goes in the strong direstion of the pattern whereas the other one does not. (Here a 2cm displacement of the contact patch on a 80/90-14 tire, just an example to be readable)

There should be 4 pictures. There was no tire pattern difference in your pictures. The direction of movement was missing. The deformation of tire should be similar in both tire pattern orientations. When accelerating the contact patch moves forward and when braking backwards. The contact patch is more elliptical than oval.

Edited by Eucner
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On 2/9/2024 at 3:01 AM, null said:

@Eucner Let's get over with this as it has taken way too long allready, but last question: I was using the work "forces" in my first illustration because I have been using that word for energy (?) in structures. I suppose gravity is a force. Say we have a cantilever beam, subject to gravity, it pushes and pulls on its fixation point, what should then this energy be called if it is not a force? 

I don't know how this relates to the subject. Gravity is pretty constant, so not much pushing and pulling. Gravity is a force, which creates deformation in the structure.

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3 hours ago, Eucner said:

I don't know how this relates to the subject. Gravity is pretty constant, so not much pushing and pulling. Gravity is a force, which creates deformation in the structure.

I have spent hours changing this visual because you said the word "Forces" was not the correct one in the first version, I just thought you could have told me what it was after all this good will from my side. I am not refering to deformation, but to whatever "energy" (?) is travelling from "spring" to "spring". Re-reading your posts it is maybe "free forces"? Never mind, I am so done here.

3 hours ago, Eucner said:

There should be 4 pictures. There was no tire pattern difference in your pictures. The direction of movement was missing. The deformation of tire should be similar in both tire pattern orientations. When accelerating the contact patch moves forward and when braking backwards. The contact patch is more elliptical than oval.

- No, there doesn't have to be 4 pictures, there are only 2 different positions of the patch relative to the rest of the tire (and of coursee all the in betweens and side versions when turning, since everything has to be said). The bold text mentions which two cases each illustration reffers to.

- If you do not see the difference between the one where the groves are pushed close and the other where they are not I can not help you. I even allready told you it helped to flip between the two aftern clicking for full frame viewer. Do you think I would have spent time on two illustration where there was no difference?

- That information is baked into the sentences in bold "when braking as front tire" and "when accellerating as rear tire", (and their opposite) as well as showing the neutral center position and the moved position of the contact patch. The information is there, it is just not in the form you prefer, or bothered to understand.

- Yes, that is what my illustration show, albeit without arrows because I'm tired ow wasting time on this. The information is there, in text. Do you think I just made a random picture without knowing where the patch was moving?

- Yes, it is a symbolic contact patch, I guess I should have specified that it could be of different size and shape as well. I guess the word "approximation" in the title and "not entirelly correct" in the comment wasn't enough, my bad.

--

Till now I could push myself to think your nit-picking and "not understanding" was good natured, now I do not think so. I believe you are getting high on feeling superior by trying to humiliate me. At best you are "on the spectrum", but I do not think so. I will no longer try to be helpfull to the community by making illustrations if it's for getting jumped in this way. And note that it isn't that I can't take criticism or correct an error, I have accepted a lot. It is your boderline insulting stance which is the issue. I will also no longer read nor address you.

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44 minutes ago, null said:

I have spent hours changing this visual because you said the word "Forces" was not the correct one in the first version, I just thought you could have told me what it was after all this good will from my side. I am not refering to deformation, but to whatever "energy" (?) is travelling from "spring" to "spring". Re-reading your posts it is maybe "free forces"? Never mind, I am so done here.

Actually at the first I said your force arrows were in wrong direction. Then I said the arrows were in the direction of displacement. It's your presentation and up to you if you want to show forces, displacement or something else. Just label it correctly and have right direction.

44 minutes ago, null said:

- No, there doesn't have to be 4 pictures, there are only 2 different positions of the patch relative to the rest of the tire (and of coursee all the in betweens and side versions when turning, since everything has to be said). The bold text mentions which two cases each illustration reffers to.

- That information is baked into the sentences in bold "when braking as front tire" and "when accellerating as rear tire", (and their opposite) as well as showing the neutral center position and the moved position of the contact patch. The information is there, it is just not in the form you prefer, or bothered to understand.

- Yes, that is what my illustration show, albeit without arrows because I'm tired ow wasting time on this. The information is there, in text. Do you think I just made a random picture without knowing where the patch was moving?

When acceleration and braking the thicker part of tire will be on the different side of contact patch. Hence there is 4 different cases. You can condense them into 2 pictures, if you add 2 arrows showing moving direction for accelerating and braking.

44 minutes ago, null said:

- If you do not see the difference between the one where the groves are pushed close and the other where they are not I can not help you. I even allready told you it helped to flip between the two aftern clicking for full frame viewer. Do you think I would have spent time on two illustration where there was no difference?

I followed your orders, and that's how I found errors in pictures. I didn't ask you to make any pictures. It has been your free choice all the time. I've spend some time trying to help you, and that's my free choice.

44 minutes ago, null said:

Till now I could push myself to think your nit-picking was good natured, now I do not think so. I believe you are getting high on feeling superior by trying to humiliate me. At best you are "on the spectrum", but I do not think so. I will no longer try to be helpfull to the community by making illustrations if it's for getting jumped in this way. And note that it isn't that I can't take criticism or correct an error, I have accepted a lot. It is your boderline insulting stance which is the issue. I will also no longer read nor address you.

Your pictures will be helpful when they are correct. I assume that's also your goal. I'm sorry if I haven't been able to be clear enough in my communication. I feel you not being fair to me.

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