tyre graining

[cavalino]

Can someone explain me what is actually tyre graining.

thank you!

[-shr3d-]

hey cavalino,
no expert on this by any stretch but im sure someone will correct me where im wrong, i hope.
i believe that tyre graining is when the top layer of rubber on the tyre is damaged (i think it may roll into little balls similar to the marbles discarded on the track but not sure) by excessive lateral load on the tyre caused when turning tight corners at high speed. This induces understeer which aggravates the problem.
Usually happens on new tires that havent been prepared properly which was why in 01 -02 the williams spent most of practice preparing tires for the races. Michelin seem to have found a better solution to this problem at the moment than Bridgestone have.
any further details or corrections gratefully accepted.

[Monstrobolaxa]

Well I'm not to sure about this.....but....imagine a piece of sand paper....try passing it on rubber!.....it damages the outter layer of rubber like sh3d said!.....it might be something like that....but if F1 you do't have sand paper!!!!you have the track!!! hahahahaha

But it must be something like that! I seen it in kart.....

[ced ampo]

Tyre graining is as simple as one tire wearing out faster than the others.

[modbaraban]

Tyre graining is as simple as one tire wearing out faster than the others.

Is it? Why did it acquire a specific term then? I think graining as you describe it happens normally.

PS: some archeology going on here lol

[Ciro Pabón]

First, welcome, ced_ampo. I've been busy lately and I'm not behaving like a good host, so this is your first post (for me).

So, get this: allow me to differ. Graining happens when you overwork your tyres before heating them.

I repeat: it's lack of patience what gives you graining, not a bad setup. Tell me that is my fault as mechanic when is yours as a driver and I get angry.

If, as ced_ampo says, a driver claims that graining happens just because a tyre is wearing too much, he is implying that he has a failure of the setup. Actually, graining is normally the driver's fault. Do not blame others so quickly before you're enlightened or you might get into trouble with your mechanics... and believe me, you do NOT want to get into trouble with them. Fight the manager, that's what he's there for.

Here you have some pictures, to make it short (thanks, master DaveKillens for the source of the pictures: The Racing & High-Performance Tire, Sports Car, March 2004). This is also archeology, modbaraban, I got them from a previous thread.

Abrassion (top row) vs. graining (lower row). Pictures to the right are magnified. Slight difference, eh? However, it's crucial.


Front tyre, normal wear ("Good run, kiddo! I think we got the basic setup" )


Front tyre, grained ("What are you doing, kiddo? You toasted your tyres, for the love of Pete!" )


Rear tyre, slight graining on the inside (bottom of the picture: get close to the monitor or you won't see it ). Slippage during acceleration? ("Hey, kid, is this your first time with this kind of power? Easy on the throttle, pleeze!" Also, it could be excessive camber... think twice before talking to your driver)


Finally, blistered tyre.

Vulcanization reversed because of heat, but, normally, it's not the driver's fault: I'd bet on an onverinflated tyre. It generates heat at the level of the ply and the heat "works" the tyre from below


Why graining happens:

During sliding, deflection waves in the rubber turn into peaks which are bent over, exposing the upstream side to abrasion. The peaks wear thinner into teeth and the tips are eventually torn off.


Tip: graining is sometimes hard to see, but is always easy to feel (it's exactly like love! Latinos here will get my point.) A good mechanic always "caresses" the surface of the tyres to know what's going on. Check the initial picture: it's easier to "feel" the tyre than to get a microscope. You can feel the little "nipples" easily.

Gosh, I'm going OOT again.

Is that clear?

[modbaraban]

Thank you.

[ClioSport197]

Many thanks Ciro Pabón for the in depth description. Very interesting!
However, I don't have any experience with slicks tyres as the cars I work with use treaded Avon control tyres. So my question is can you get graining on treaded tyres as well?

[Jersey Tom]

Yes, you can.

This, by the way..


I would not consider graining. It is a separate problem tied into the manufacturing of the tire. I bet that's a Hoosier, too..

[Ciro Pabón]

No, JTom, no manufacturing problem, or so I think: it's graining, or so says Paul Hanlin in the book I mentioned, here. Chapter 8 of that book appeared in Sports Car magazine, as I explained.



Perhaps what I s¡should've commented about the picture is that it shows extreme graining. Simple: that's what you get in an oval. NASCAR is a thing for "machos", like us. For example, I would've loved to watch Max Mosley trying to increase Dale Earnhardt's license fee...

[sdimm]

I thought graining occured when a tire got up in to much temperature making the rubber "melt" sort of.

There for making it move across the surface and giving less grip. Also why the rubber gets torn off and destroying the tyre.

[Ciro Pabón]

Sdimm, I think you're right: if you're aggresive with a heated, "grippy" tyre, you get graining. Also, as I said, if you overwork a cold tyre. The "inner" heat provokes blistering.

[Jersey Tom]

I've met Paul.. and I've seen the book. Still not graining But I'm not sure if I can get into what it is. His book isn't bad, but take a lot of it with a grain of salt.

The spacing and regularity of those "grooves" are what gives it away. Plus you can see the rubber between them looks pretty much just fine.

Regarding what graining is.. I think of it as exceeding the tear strength of the material. Overstressing and abrading it and tearing it up. Can happen cold ("cold tearing") or hot ("graining") depending on the material properties.

[modbaraban]

I made a little search and found this.

[timbo]

I made a little search and found this.

I think that left image is not graining, it is that worn rubber that they pick up from track at the end of the race before weighting. The tyre itself seems to be in good shape.