F1technical.net

I hope that someone can help understand the difference between graining and blistering. As far as I understand graining is the phenomenon(!) when a tyre gets (literaly) a new 'groove'. Is that the case? If not could someone explain me what's the difference between graining and blistering?

Don't they contribude to tyre overheating?

Thanks!

I don't hear much about graining but blistering is when chunks of the tire come out due to overheating.

I'm sure you've burned yourself at one point on your life to the point where you've had blisters. Well, same thing...

This is the end result:

ya i have that on like one of my tires, i think the outer rim of the left front

Graining and blistering are two different things that can happen to tires, but are related in that they are bothusually a result of low air pressure, or to aggressive driving. This article gives an excellent explanation. I suggest anyone seeing this post bookmark this one.
http://www.insideracingtechnology.com/tirebkexerpt3.htm

Great link Dave, I'm going to have to get his book. Finally, I actually understand what slip angles are all about. Tire tech is so secretive, it's great to read somebody so knowledgable on the subject, quite rare.

Great site for race tech info. Also has a great links page.

Yes, Dave, thanks.

I dare to recommend (again!) this explanation on slip angle. There are more if you want to keep reading (Chapters 19, 24 and 25, but it gets pretty complicated).

We (or at least tire companies) have now a complete model of tire and road interaction. I like this guy, who solved the tire equations, apparently once and for all (Bo Persson):



I already tried to explain his revolutionary theories on another thread, in case you are interested. You will find the links and one of my "stratospheric" explanations there.

Blistering

Massive acceleration and extreme loads in fast corners may overstrain certain areas of a tyre, resulting in blistering

Graining

When sliding sideways, rubber may peel off the tyre, something that usually happen to the front tyre, causing understeer.

@Jason:

Well, you are right, but it seems they are not well differentiated in your explanation. Dave link explains it clearly. The links I gave explain it too, but I guess you did not buy the articles I recommended (no wonder at U$28 each). What I got is this:

Graining occurs by friction with pavement. Actually, F1 tires are "dried" and after they lost the "liquid phase" they disintegrate.

Blistering occurs by inner friction. The layers of the tire bend every revolution, they rub against each other, and this produces heat. This heat moves outward and separate the rubber from the inner layers of the tire.

So, graining occurs at curves and braking/accelerating zones. You need to change the rubber or the asphalt to alleviate it.

Blistering occurs anywhere, as long as the wheel is rotating. You do not need friction with pavement for it to occurs. You need to change the inner structure of the tire or the heat carachteristics of the rubber to alleviate it.

Both are affected by tire pressure and load, as you can deduce, but I would guess that the blistering could be dimished if you inflate the tire, because it flexes less, but you will get more graining because you diminish the contact patch size.

If this is true, as Jason's post says, a blistered tire can happen easier on a high-speed circuit, with long straights and big radius curves, where the tire is rotating and flexing at high speeds while is hot.

A grained tire would be characteristic of a "chicaned and hairpined" circuit (I mean a short-straights and small-radius-curves circuit). Here the tire is used to brake and turn at relatively slow rpm's.

could people like not like use the word "like" like when its not like needed?

Particularely the NASCAR commentators, every 2nd word is like or you know. It is hillarius for a few minutes but quickly gets teadiouse.

Can people (pyry) like stop moaning about pathetic things

pyry wrote:could people like not like use the word "like" like when its not like needed?

Whatever you say, pyry, whatever you say. Cool, man, put the gun down slowly...