Tyre load sensitivity

[w126]

Let's compare two graphs. One is here http://www.carbibles.com/tyre_bible.html just after 'tyre load sensitivity' phrase (use 'Find in this page' browser function). It shows tyre load sensitivity for lateral forces. The other graph (see the attachment) shows the same but for LFS road super tyres (RB4). The data for it are extracted and derived from RAF. More info and tools are in this thread http://www.lfsforum.net/showthread.php?t=3667. I hope the data are correct and accurate enough.

The first graph ends at around 7 degrees of slip angle, but nevertheless it's hard to imagine that the curves plotted for different load values converge for larger slip angles. However in the second graph (LFS data) the curves seem to converge for larger slip angles, as if load sensitivity effect disappeared then.

How can this influence car handling? I think load sensitivity may help recovering from drifts, because less lateral weight transfer (achieved by slowing down or increasing turn radius) means more effective grip for both wheels of the same axis taken together. Now imagine rear wheels at slip angles over 14 degrees in LFS. It seems we lose this positive effect of load sensitivity in that case.

I may be wrong, in fact it's very likely. ;) However as I'm posting it in Suggestions subforum I just wanted to say that maybe it is worth analysing this aspect of tyre behaviour one more time. Good luck!

[axus]

Well, first of all, one would have to compare tyre sizes and pressures. A lower pressured tyre would twist more generating a greater slip angle. So would a higher profile tyre and I also think that a thiner tyre (in terms of width) twists more but I'm not too sure of this.

EDIT: Not to mention suspension dynamics which would have a huge effect on this... if you could find what car that data is from, we could attempt to recreate that car in LFS while getting the suspesnsion settings as close to it as possible. Then we can get some real data... before that there are just way too many factors that could throw the results off.

[w126]

Yes, you are right. These two graphs are definitely for different tyres with different sizes and pressures. I forgot to add that I didn't mean the exact comparison of the graphs, but rather treating the first graph as a typical example of load sensitivity data and comparing only the basic properties of the two graphs, like if the curves converge or not.

[Bob Smith]

I can't get the original image to compare with. The graph for LFS seems quite reasonable from what I can remember from similar graphs that I've seen before.

[w126]

My mistake. I edited the link to the original image in the first post.

Yes, the graph for LFS is reasonable. The only strange thing is that for slip angles over 14 green, black and blue points become very close.

Not to mention suspension dynamics which would have a huge effect on this... Influence of suspension is largely eliminated, because data for the graphs are measured in standardized (SAE) 'tyre-road' coordinate system, forces are forces acting on tyres, some parameters already account for suspension influence (tyre to road camber).

[axus]

I have been reading the thing about tyre width on there and it is becoming enough to make me throw up... very interesting though. Not much has sunk in yet. I will re-read it sometime, when my brain is functioning at full capacity.

[B2B@300]

Scawen alluded some weeks ago that he was going to be coding a virtual test rig to analise tyre dynamics and my guess is he would be able to get some pretty reliable tyre data, so I'd think that this is already on his agenda amoung other things :scratchch

[axus]

Scawen alluded some weeks ago that he was going to be coding a virtual test rig to analise tyre dynamics and my guess is he would be able to get some pretty reliable tyre data, so I'd think that this is already on his agenda amoung other things :scratchch

On his agenda it may be, however good information and research such as that link is always useful, and if he is linked to it rather than finding it himself it could save him some time. :)

[B2B@300]

On his agenda it may be, however good information and research such as that link is always useful, and if he is linked to it rather than finding it himself it could save him some time. :)

Agreed with you there Axus but I don't think we can find too much more than he has already found as I'm sure he is able to do a google search like the rest of us :tilt: (I came accross that site several weeks ago after a quick search also) but it's not a waste as it educates us and makes the average pleb appreciate just how difficult a task it is :scratchch

The really good info that might be able to be obtained requires the handing over of some cash, which I'm sure the SEV have done in there quest for good information and reliable research :shrug: as have many other developers of simulation games... not to mention LFS ties with the MRT and RAC :shy:

[Thomas Fink]

The friction behaviour of a tyre at high slip angles approaches that of a nearly locked tyre at braking. And there the heavier loaded tyre has a higher friction force. Of course there are other effects too like the warping of the tyre structure but in the end friction is the most important factor. (Unless the tyre jumps off the rim)

Edit: The above is only valid for the force but not for the friction coefficient that is in the plot. So please ignore it.....