Define: Tyre Grip

[mzivtins]

No bonus points for the obvious, but what i want to know is:

Where we talk about the 'Grip' of an F1 tyre (p zero or any type of F1 tyre) we always talk about the tyre being warm and in some cases 'sticky'

As the tyre reaches its optimal operating temperature does this improve grip by either allow the tyre to 'tread' into the surface, or does the chemical that we call 'rubber' actually give an adhesive quality? Or are we looking at both?

The reason i ask this question is because of the very unique surface of the Indianapolis motor speedway, i just wonder if the added groves given by the brick layout would in some way allow the tyre to step into the void between the brick and improve adhesion?

I know the obvious comparison would be to compare the void between the bricks to tread cut into tyres, my instincts would tell me a bricks surface might be better under braking, but awful in corners. So what makes a tyre stick? and dont say Peter Sauber

[Jersey Tom]

Tire forces at the road interface have a number of components, including hysteretic loss and adhesion, yes. There are some public domain documents on rubber friction and tribology to this end.

Indy is unique in how it is ground, yes... but really every racetrack has its own character of the surface. Indy has grooves, some others are very flat with new pavement and only small irregularities... older tracks may have larger scale irregularities due to the aggregate having been beat up.

You'll note I was careful to never mention the word "grip."

[superdread]

The only really contributing mechanism is mechanical adhesion (as in static and dynamic friction), isn't it?

In that terms surface area and load is everything. This is possible on a macroscopic scale (the tyre is a flattened cylinder-like object) and a microscopic one (the surface is a more or less deformable mass being pressed into the hilly surface of the asphalt).

This easily illustrates some contributing factors:
- load on the wheel (therefore car weight, downforce, suspension setup)
- softness of the rubber (rubber penetrates deeper into asphalt -> more surface area)
...

This model only illustrates why a tyre gives grip in any one moment, given the conditions it's in. Managing a tyre (e.g. its temperature) over any sort of distance is a whole different matter.

[Jersey Tom]

The only really contributing mechanism is mechanical adhesion (as in static and dynamic friction), isn't it?

Mechanical adhesion being what?

[Nando]

Indy? I thought the only brick layout there was a strip on the start/finish straight.
I.e 1 millisecond and you have passed over it.

[Jersey Tom]

I just realized the OP was talking about the bricks!

It is unique though in the diamond grinding:

[Pierce89]

I just realized the OP was talking about the bricks!

It is unique though in the diamond grinding

These grooves gave Nascar and Goodyear hellacious trouble a few years back!

[raymondu999]

Weren't they the object of the Indy GP 05 debacle too?

[hardingfv32]

What was the purpose of the grinding? Does it represent a long term solution?

Does the grooved surface represent a net gain in grip compared to a non-grooved surface?

Brian

[superdread]

The only really contributing mechanism is mechanical adhesion (as in static and dynamic friction), isn't it?

Mechanical adhesion being what?

Two rough surfaces being pressed together and then pulled along each other. The adhesive effect is only parallel to the contact patch and is caused by interlocking of the rough surfaces.

[mzivtins]

Interesting replies, thank you guys, i understand how we would classify 'grip' or more that 'grip' is a nice word to group together a large number of factors overall.

But when we look at the grooves posted, and as i mentioned the brick for indy, could the voids in the grooves give added 'grip'? would braking hard on a bricked surface give more grip than a smooth surface?

Sort of like how the 'anti-skid' we see on the road and the run off areas of race tracks work, uneven surface gives more for the tyre to urm, mould?, against? i could imagine driving hard on this surface would increase tyre wear?

[riff_raff]

With regards to grooves in the track surface, I would imagine that all other things being equal the track grooves would create higher temperatures in the tread structure. The grooves would reduce the contact area at the tread, and for a given amount of heat transfer occurring between the tread and track, more heat would be forced into the tread surface.

[Richard]

This conversation isn't complete without ref to one of the best old threads on here viewtopic.php?f=6&t=9333

[mzivtins]

That is an awesome thread! So the non smooth surface causes more 'interlocking' and the smoother surface allows the tyre to be more 'sticky'

So really, in an answer, tyre 'grip' is a good name for all modes of friction.

[ubrben]

So really, in an answer, tyre 'grip' is a good name for all modes of friction.

Important to remember that when a driver uses the word grip he doesn't necessarily mean (and often rarely means) the friction coefficient as we'd define it in an engineering sense

Ben