Goodyear Asymmetry

[slippery_pete]

So the last few iterations of tires produced by goodyear have an asymmetric sidewall construction.

My question is when running the tire at zero slip angle and zero camber, does it push in towards the centre of the car, or outwards from the centre of the car?

I know NASCAR tires have a stiffer inner sidewall to create the effect of negative camber on their rear axle since they are limited on how much physical camber they can put in. My question is; are the FSAE tires made in the same way?

When you look at TTC tire data the goodyear's clearly produce higher ultimate grip in the direction the tire 'pushes' when rolling straight ahead which makes sense if they push inward. This is the assumption I have always operated under but recently I have had it sworn up and down to me that it is the other way.. hence the question.

[slippery_pete]

So the last few iterations of tires produced by goodyear have an asymmetric sidewall construction.

My question is when running the tire at zero slip angle and zero camber, does it push in towards the centre of the car, or outwards from the centre of the car?

I know NASCAR tires have a stiffer inner sidewall to create the effect of negative camber on their rear axle since they are limited on how much physical camber they can put in. My question is; are the FSAE tires made in the same way?

When you look at TTC tire data the goodyear's clearly produce higher ultimate grip in the direction the tire 'pushes' when rolling straight ahead which makes sense if they push inward. This is the assumption I have always operated under but recently I have had it sworn up and down to me that it is the other way.. hence the question.

[Edward M. Kasprzak]

Have you looked at the TTC data at zero slip angle and zero camber angle?

[exFSAE]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by slippery_pete:
So the last few iterations of tires produced by goodyear have an asymmetric sidewall construction.

My question is when running the tire at zero slip angle and zero camber, does it push in towards the centre of the car, or outwards from the centre of the car?

I know NASCAR tires have a stiffer inner sidewall to create the effect of negative camber on their rear axle since they are limited on how much physical camber they can put in. My question is; are the FSAE tires made in the same way?

When you look at TTC tire data the goodyear's clearly produce higher ultimate grip in the direction the tire 'pushes' when rolling straight ahead which makes sense if they push inward. This is the assumption I have always operated under but recently I have had it sworn up and down to me that it is the other way.. hence the question. </div></BLOCKQUOTE>

Might want to do some fact checking.

[Zac]

is it an asymmetric sidewall or is it an asymmetric footprint?

[slippery_pete]

The NASCAR thing I read in a book about tires, so maybe that's not true anymore, or was never true.

Dr. Kasprzak, when I look at the TTC raw data, nondimensional model, and the pacejka model they are not consistent with their axis definitions. The pacejka model is flipped about the x-axis versus the other two. This is a source of confusion..

In the latest round of TTC they don't say they run the Goodyear's label in and label out, and any camber they put in cancels out the straight ahead lateral force, in which case you would think they push out.

In any case I have thoroughly confused myself and would rather not do all my work this year backwards! I feel like this shouldn't be this confusing, I appreciate the help.

[Adambomb]

As I recall the TTC test data was all taken "label out," as they were intended to be run. I think it mentioned that in one of the .pdfs that came with the data. And as I recall plotting the data, if you use an IA input set at 0 deg., you do get interesting results...

[Edward M. Kasprzak]

I have written a detailed reply on the TTC's private forum, http://sae.wsu.edu/ttc/ It's on the "Tire Testing" page.

slippery_pete, if you're not registered there please go to the site and sign-up. Approval takes a day or two.

The private forum is a much better place to discuss TTC questions, since everyone there is a member and we speak openly about the data, share plots, etc. We aren't as open here to protect the investment made by member schools.