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

[sofaking]

Vex,

Okay, I can see how I misinterpreted the MoS thing. The point about not being at max load wasn't as much a reference of the fact that it determines the whole criteria, but that it plays a role in the original engineering specifications. When I say that it's not at its maximum rating on an average vehicle I'm just saying that if it isn't at it's maximum load then changing the load (large assumption here) might have some wiggle room. <-I know there's no way you'll concede to that point.

I had to read the gun reference a couple times to pick up the point you were making there, still not 100% sure I understand what you're saying about the non-firing round. (I'm not a gun person, I stay away from them.)

I did understand the brake master reference. That's an excellent reference for anyone that has driven with a leaking brake master. I could definitely see how the two correlate. That's your best argument yet for real world relation IMO. (this was the thing I was trying to do previously with coffee and baseball bat references, it's hit and miss sometimes with metaphors)

Your reply of "Not really" is the point I've been trying to make the whole time. If you didn't see ANY validity in what I said you would've answered "No", but you did see some truth in what I'm saying. You don't agree with it as being safe by engineering standards, but obviously have to accept that the possibility that it will hold is true. I am willing to more directly concede. My only point this whole time was to get acknowledgement that it's possible it's safe (from a standard of holding for the life of the tire). I'm not saying it is, I agreed with your statements of material sciences from the get-go and agree that there will be deformation on the tire. All I've argued is that it's possible that it will hold and get you safely from point A to point B for the life of the tread. I understand your stance of safety and agree that there is definitely a possibility that it could fail as well based on using it outside of its designed specifications.

For the vulcanized rubber, where am I looking this up and what types of numbers am I looking for?


And as for the VIP Celica... that thing is awful. Also, there's no way I'd be willing to stretch a tire that far. I am definitely not arguing for what that guy is doing. That shit is wrong on so many levels.

[vex]

Please quote my previous response as it makes things easier to keep track of.

Originally Posted by sofaking

Vex,

Okay, I can see how I misinterpreted the MoS thing. The point about not being at max load wasn't as much a reference of the fact that it determines the whole criteria, but that it plays a role in the original engineering specifications. When I say that it's not at its maximum rating on an average vehicle I'm just saying that if it isn't at it's maximum load then changing the load (large assumption here) might have some wiggle room. <-I know there's no way you'll concede to that point.

Honestly there's too much variability to say for certain. For a regular all terrain tire it very well may have enough 'room' to work in a stretched application as their made with different constraints in mind where as high performance tires with high speed ratings may not (lean manufacturing; basically means that the FoS gets closer to 1).

I had to read the gun reference a couple times to pick up the point you were making there, still not 100% sure I understand what you're saying about the non-firing round. (I'm not a gun person, I stay away from them.)

That's fine. It's the same as the master cylinder analogy.

I did understand the brake master reference. That's an excellent reference for anyone that has driven with a leaking brake master. I could definitely see how the two correlate. That's your best argument yet for real world relation IMO. (this was the thing I was trying to do previously with coffee and baseball bat references, it's hit and miss sometimes with metaphors)

Your reply of "Not really" is the point I've been trying to make the whole time. If you didn't see ANY validity in what I said you would've answered "No", but you did see some truth in what I'm saying. You don't agree with it as being safe by engineering standards, but obviously have to accept that the possibility that it will hold is true. I am willing to more directly concede. My only point this whole time was to get acknowledgement that it's possible it's safe (from a standard of holding for the life of the tire). I'm not saying it is, I agreed with your statements of material sciences from the get-go and agree that there will be deformation on the tire. All I've argued is that it's possible that it will hold and get you safely from point A to point B for the life of the tread. I understand your stance of safety and agree that there is definitely a possibility that it could fail as well based on using it outside of its designed specifications.

Not to be a dick, but that's a contradiction. Safety does not include taking a chance where it can be eliminated. Sure you could get to point A to point B, but will you make it every time with a stretched tire? It's the same issue with the leaking MC. How often can you make that trip with the cylinder like that? Once? Twice? Forty? It's a gambit at best.

For the vulcanized rubber, where am I looking this up and what types of numbers am I looking for?

Check the Matweb website, I found this one, but if you want to use a different rubber feel free to find it:
http://www.matweb.com/search/DataShe...ff3f5da&ckck=1

We want the mechanical properties.

[sofaking]

Originally Posted by vex

Not to be a dick, but that's a contradiction. Safety does not include taking a chance where it can be eliminated. Sure you could get to point A to point B, but will you make it every time with a stretched tire? It's the same issue with the leaking MC. How often can you make that trip with the cylinder like that? Once? Twice? Forty? It's a gambit at best.

I agree. The more things that are outside of design the higher the risk. I would agree risk goes up with tire stretching. In your opinion would you think that it is more dangerous to blow out a stretched tire than a blowout for any other reason? If so, why? Obviously this is a reference to driving within the laws of the road you're traveling on, not assuming some sweet jdm drift battle on the mountain with a bunch of morons trying to get youtube footage with thier friends in the car.

Originally Posted by vex

Check the Matweb website, I found this one, but if you want to use a different rubber feel free to find it:
http://www.matweb.com/search/DataShe...ff3f5da&ckck=1

We want the mechanical properties.

I also found this one (and a couple others of different particle mesh size) but no mechanical properties are listed.
http://www.matweb.com/search/DataShe...0718874&ckck=1

I didn't see a way to post it here that would be easy to read so I separated the fields using astrix..

Mechanical Properties *** Metric ***** English ***** Comments
Hardness, Shore A ****** 30.0 - 100 *** 30.0 - 100 *** Depends on compounding
Hardness, Shore D ****** 30.0 - 45.0 *** 30.0 - 45.0 ** Depends on compounding
Tensile Strength, Ultimate * 28.0 MPa **** 4060 psi **** Compounded Tire
Elongation at Break ****** 100 - 800 % ** 100 - 800 %
100% Modulus ********** 0.00150 GPa ** 0.218 ksi
Shear Modulus ********** 0.000500 GPa * 0.0725 ksi

Would you mind explaining what the "elongation at break" field means? It seems at a glance that it would mean that it can stretch 1-8x its length before breaking... that seems like a HUGE range.

[vex]

Thanks for quoting.

Originally Posted by sofaking

I agree. The more things that are outside of design the higher the risk. I would agree risk goes up with tire stretching. In your opinion would you think that it is more dangerous to blow out a stretched tire than a blowout for any other reason? If so, why?

Yes. As the tire is already stressed outside of spec; damage to the wheel is more than likely to result (not to be confused with the tire). Normal blow out allows for material sacrifice to save the wheel. This is of course dependent upon the amount of stretch on the tire. The closer the stretch is to stock spec the more material will be available to sacrifice in maintaining the wheel.

Obviously this is a reference to driving within the laws of the road you're traveling on, not assuming some sweet jdm drift battle on the mountain with a bunch of morons trying to get youtube footage with thier friends in the car.

I also found this one (and a couple others of different particle mesh size) but no mechanical properties are listed.
http://www.matweb.com/search/DataShe...0718874&ckck=1

I didn't see a way to post it here that would be easy to read so I separated the fields using astrix..


Would you mind explaining what the "elongation at break" field means? It seems at a glance that it would mean that it can stretch 1-8x its length before breaking... that seems like a HUGE range.

Elongation at break is the elongation of the material at catastrophic failure during a tensile test. During material testing they install a test piece similar in design to these:

Elongation is the final distance (if given in percentage the final distance divided by the original) the sample is able to make it. This is not the same as failure (encroachment into plastic region of deformation).

[sofaking]

Originally Posted by vex

Yes. As the tire is already stressed outside of spec; damage to the wheel is more than likely to result (not to be confused with the tire). Normal blow out allows for material sacrifice to save the wheel. This is of course dependent upon the amount of stretch on the tire. The closer the stretch is to stock spec the more material will be available to sacrifice in maintaining the wheel.

I don't mean more damage to the things I own. I mean more dangerous. I.E. am I more likely to die or more kill someone else based on a blow out because of a stretched tire instead of a non-stretched tire? In my experience when you have a blow out you're driving on a shitty little band of rubber wrapped around the wheel flopping around like an epileptic on meth. Would a blow out with a stretched tire be worse or harder to control in some way?

Originally Posted by vex

This is not the same as failure (encroachment into plastic region of deformation).

The explaination was what I was looking for (the picture helped). I wasn't relating this to tires though, I was just wondering why the technical information about the material had such a wide range of data. Seems either really unpredictable or there is a lot of data that we aren't getting. I would imagine to have an 800% discrepancy there would have to be a lot of tests with different compounds, temperatures, etc.

[vex]

Originally Posted by sofaking

I don't mean more damage to the things I own. I mean more dangerous. I.E. am I more likely to die or more kill someone else based on a blow out because of a stretched tire instead of a non-stretched tire? In my experience when you have a blow out you're driving on a shitty little band of rubber wrapped around the wheel flopping around like an epileptic on meth. Would a blow out with a stretched tire be worse or harder to control in some way?

Yes it would be more dangerous as you would be trying to drive on metal instead of rubber. The dynamic coefficient of friction is small when compared to rubber, thus control is going to be more difficult. If the blow out happens on the front you will have very little or no response from that tire. The rears will be similar. This is of course holding that the failure is on the material side of things.

The explaination was what I was looking for (the picture helped). I wasn't relating this to tires though, I was just wondering why the technical information about the material had such a wide range of data. Seems either really unpredictable or there is a lot of data that we aren't getting. I would imagine to have an 800% discrepancy there would have to be a lot of tests with different compounds, temperatures, etc.

Tests are standardized. Temperature is a variable that can be tested for as for different mixtures of vulcanized rubber (that's where the proprietary rights begins coming in).

[sofaking]

Originally Posted by vex

Yes it would be more dangerous as you would be trying to drive on metal instead of rubber. The dynamic coefficient of friction is small when compared to rubber, thus control is going to be more difficult. If the blow out happens on the front you will have very little or no response from that tire. The rears will be similar. This is of course holding that the failure is on the material side of things.

I've never had a stretched tire blow out on the streets. But I've taken it on the track knowing that I've only got another lap and 1/2 left on the tires and go anyway just because it's funny to hear a tire blow out (not on tracks with walls). I've never damaged a wheel driving it back to the pits. I have however scratched the crap out of the side of my car when a non-stretched tire de-laminated on me and the tread swung down the side of my quarter panel repeatedly until I got into the pit. I've not noticed a difference between a stretched and non-stretched tire poping from going past the cords. If the material was the part that failed this should result in the sidewall blowing out? Then what's left of the sidewall would fold over resulting in driving on the wheel?