F1technical.net

That's why we have JT speaking like Yoda all of the time!

mx_tifoso wrote:Changing the rolling resistance characteristics will not have a significant impact on grip? For some reason I doubt it.

There are of course some relations obvious to the engineer, such as;

- A wider tyre should have both higher rolling resistance as well as better grip.
- A lower tyre pressure will cause much higher rolling resistance but also a larger contact patch.

Hey Z, you are pretty good at copy'n paste from Wiki, eh?

@ Ray; I'm not certain that comparison is relevant?

Yes of course X, but we shouldn't add different sizes to the equation, or significantly different pressures.

Michelin talk a lot about this and I'm looking around for some good articles as we speak.

mx_tifoso wrote:Yes of course X, but we shouldn't add different sizes to the equation, or significantly different pressures.

Michelin talk a lot about this and I'm looking around for some good articles as we speak.

I agree, that's why I didn't bring those parameters up to begin with.

You might be right mx, logically speaking, a more compliant tyre-sole should perhaps offer both less hystresis and better grip?

Right, providing a constant contact patch despite lateral movement increases grip. So given that and a fixed size and pressure, the only (?) variable left when relating it to rolling resistance is the compount, as mentioned in the article.

And perhaps we should limit this discussion to the realm of racing? Seeing how road tyres throw in other requirements such as wet weather performance which in turn affects the compounds and construction, and not to mention treads.

xpensive wrote:

mx_tifoso wrote:Changing the rolling resistance characteristics will not have a significant impact on grip? For some reason I doubt it.

There are of course some relations obvious to the engineer, such as;

- A wider tyre should have both higher rolling resistance as well as better grip.
- A lower tyre pressure will cause much higher rolling resistance but also a larger contact patch.

Hey Z, you are pretty good at copy'n paste from Wiki, eh?

@ Ray; I'm not certain that comparison is relevant?

not really X..i learned that in m physics course

amouzouris wrote:so here is my question... how do they engineer into the tire a high grip level but with a low rolling resistance??? they seem to contradict each other..

They don't. You trade off one for the other, unless you find some new way of doing things that lets you get a little of both at the same time. The tricks to that are proprietary.

Just as well could be asking, "How do you make an engine more powerful and use less fuel?" You don't, it's a trade off - unless you make some fundamental efficiency gain.

That's what I thought occurred, but I didn't want to assume without more legitimate feedback. And thank you for the fitting analogy.

Yes, it's a tradeoff, but there is *some* tuning that can be done, because rubber responds to the frequency of inputs. And the frequency for rolling resistance at a given speed is likely somewhat different than the frequencies needed for grip response (which depend on the asphalt and other factors). So for a given application, you can optimize the compound a bit.

Jersey Tom wrote: ...
The tricks to that are proprietary.
...

I'm shocked.

Jersey Tom wrote:

amouzouris wrote:so here is my question... how do they engineer into the tire a high grip level but with a low rolling resistance??? they seem to contradict each other..

They don't. You trade off one for the other, unless you find some new way of doing things that lets you get a little of both at the same time. The tricks to that are proprietary.

Just as well could be asking, "How do you make an engine more powerful and use less fuel?" You don't, it's a trade off - unless you make some fundamental efficiency gain.

well that was exactly my question what is that breakthrough that allows you to reduce rolling resistance without the trad of...and ofc they are proprietary (good one X ) ...the link mx posted is a good place to start

To say that you can trade grip for less rolling resistance and vice-versa is a new one, at least to my humble self.
Rolling resistance comes predominantly from the tyre's hysteresis, which I tried to xamplify above, while "grip" is something different, stemming from classic friction "mu", as well as contact forces in the irregularities of the road surface.

xpensive wrote:To say that you can trade grip for less rolling resistance and vice-versa is a new one, at least to my humble self.
Rolling resistance comes predominantly from the tyre's hysteresis, which I tried to xamplify above, while "grip" is something different, stemming from classic friction "mu", as well as contact forces in the irregularities of the road surface.

A large portion of traction comes from energy loss (hysteresis) of the tread. Can read more on that topic here.

As for tricks of getting good grip AND rolling resistance... from a quick Google search it looks like the main thing I had in mind isn't particularly confidential and is plastered all over the internet.

The basic concept is that while energy loss is directly related to both traction and rolling resistance... traction comes from high frequency excitation (think of sliding over all the small bumps and asperities in a road) whereas rolling resistance comes from the once-per-revolution deflection of the whole tire - at low frequency.

Using a filler like silica instead of black let's you keep some high energy loss at high frequency for traction, but results in low energy loss at low frequency for good rolling resistance. Doing things like that is a game changer, but such things only come about every so often. Beyond that, the general trade off comes in RR (and heat) for traction.

Jersey Tom wrote:A large portion of traction comes from energy loss (hysteresis) of the tread. Can read more on that topic here.

Gee thanks, I'm sure the vast majority of the forum will study that piece in detail.

But what you are doing is xpanding into secondary parameters such as energy-loss from rolling hysteresis heating up the tyres thus making them more sticky, of which I'm not sure was the topic this time, or am I at a total loss here?

xpensive wrote:Gee thanks, I'm sure the vast majority of the forum will study that piece in detail.

But what you are doing is xpanding into secondary parameters such as energy-loss from rolling hysteresis heating up the tyres thus making them more sticky, of which I'm not sure was the topic this time, or am I at a total loss here?

First I'm too quiet, reserved, and cryptic... now too detailed?

But no, this has nothing to do with heating up tires or anything temperature related. Traction effectively comes directly from energy loss. Better read up on that *.pdf, bud!