Tire Stiffness

[mattbrooksy]

Hi There,
Could anyone give me some rough figures to use for tyre stiffness (kt)? I am using an Avon 7.0X13. From what I understand it should be roughly four times the stiffness of the spring (Kw).
Thanks

Matt

[mattbrooksy]

Hi There,
Could anyone give me some rough figures to use for tyre stiffness (kt)? I am using an Avon 7.0X13. From what I understand it should be roughly four times the stiffness of the spring (Kw).
Thanks

Matt

[js10coastr]

https://www.hoosiertire.com/spring.htm


however I think Avon's are softer.

[J. Vinella]

Making a jig to measure the tire "stiffness" is a great project for a new person.

Then you get can the data presented in that Hossier link but for your tires.

[HenningO]

Or if you have access to the FSAE TTC tire data, the spring stiffness of most of the FSAE tires are in there.

[mattbrooksy]

Thats brilliant thanks alot. I have the equipment to do the testing myself, but am struggling for design with design and fabrication of a new front end, with new dampees.
What is FSAE TTC?

[Mike Sadie]

FSAE Tire Testing Consortium

http://www.millikenresearch.com/fsaettc.html

more info can be found by searching the forum

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mattbrooksy:
Hi There,
Could anyone give me some rough figures to use for tyre stiffness (kt)? I am using an Avon 7.0X13. From what I understand it should be roughly four times the stiffness of the spring (Kw). </div></BLOCKQUOTE>

Oh yea? Why's that?

[geoffrey_khoa]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by mattbrooksy:
Hi There,
Could anyone give me some rough figures to use for tyre stiffness (kt)? I am using an Avon 7.0X13. From what I understand it should be roughly four times the stiffness of the spring (Kw).
Thanks

Matt </div></BLOCKQUOTE>

I am as curious as exFSAE on why should tire stiffness be roughly four times the stiffness of the spring? From where do you get this information?

FYI, I had read from a paper some time back that it should be roughly 10 times that of the stiffness of the spring so as to ensure that the tire is comparatively stiff as compared to the spring (however, i m still not sure of this hypothesis).

[exFSAE]

C'mon guys.. system dynamics. Multiple springs and masses operating in series. A "four times as stiff" or "ten times as stiff" rule is just BS. Rules of thumb that may or may not work for your particular application.

Changing tire rates will have an effect on force transmissability. Having a compliant tire will make for a soft system overall. Even though you may be throwing stiff springs at your car, having a really compliant tire may just drag the overall stiffness down considerably and make chassis tuning more difficult. If you wanted to make your ride twice as stiff for example you'd probably have to throw a MUCH stiffer (3x?) spring in there because the tire would be dragging the stiffness down. But it will make for a nice ride..

[geoffrey_khoa]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exFSAE:
C'mon guys.. system dynamics. Multiple springs and masses operating in series. A "four times as stiff" or "ten times as stiff" rule is just BS. Rules of thumb that may or may not work for your particular application.

Changing tire rates will have an effect on force transmissability. Having a compliant tire will make for a soft system overall. Even though you may be throwing stiff springs at your car, having a really compliant tire may just drag the overall stiffness down considerably and make chassis tuning more difficult. If you wanted to make your ride twice as stiff for example you'd probably have to throw a MUCH stiffer (3x?) spring in there because the tire would be dragging the stiffness down. But it will make for a nice ride.. </div></BLOCKQUOTE>

Thanks!