Tire compound.. overlooked in the overtaking strategy?

[Jersey Tom]

Had this thought today. Everyone wants to encourage the ability to overtake. Going to slicks is one thing in increasing mechanical over aero grip.

In order to try to get someone under the brakes or through a corner though, you have to be able to drive the tires to or beyond the limit.

With drivers seemingly not really pushing their cars to the limit to catch people under the brakes, how much of this is on Bridgestone's compounding? If you flatspot the tires or drive them too hard for a lap are they going to be uncompetitive afterward?

As opposed to a tougher compound where you might have a little less grip overall but really "going for it" isn't going to wreck what grip you have on the lap after?

[Ogami musashi]

I don't think Harder really means "less prone to reduced performance".

Hard tyres are very hard to heat and grain more than soft ones. Soft ones are often friendlier in overshoot rates and beyond the limit may behave more linearily.

No i think this is a question of construction rather.

[Jersey Tom]

Hard vs soft is meaningless in compound terminology... and you CAN have stiff compounds that come to temperature very quickly. Furthermore I'd say its much easier to grain "soft" tires than "hard."

I did say tougher, as in more resistant to abuse.

I'd still say it's much more a compound than construction parameter.

[ISLAMATRON]

Taking out the grooves will make the cars much more stable under braking. The grooves tended to make the cars squirm and move around alot under braking.

Going to slicks will increase mech grip under all (dry) conditions... most importantly when following another driver when aero produced downforce is lost and therefor grip reduced. That will be the main force behind them providing more passing oppurtunitues. I will just be happy to see more side by side racing.

really they should make a standard part of the front wing on the outside that diverts the air to the side of the car as to blow the marbles further off line... that would be a huge help towards seeing more side by side racing.

[Scotracer]

Taking out the grooves will make the cars much more stable under braking. The grooves tended to make the cars squirm and move around alot under braking.

Going to slicks will increase mech grip under all (dry) conditions... most importantly when following another driver when aero produced downforce is lost and therefor grip reduced. That will be the main force behind them providing more passing oppurtunitues. I will just be happy to see more side by side racing.

really they should make a standard part of the front wing on the outside that diverts the air to the side of the car as to blow the marbles further off line... that would be a huge help towards seeing more side by side racing.

The cars do that anyway. The airflow is not just directed over the car, it goes around the side. This air-stream is pretty damn strong.

[Jersey Tom]

I shouldn't even comment...

[ISLAMATRON]

The cars do that anyway. The airflow is not just directed over the car, it goes around the side. This air-stream is pretty damn strong.

But yet we still have a huge problem with marbles off line... a small standard aero device fitted to every car(like the camara pods) that diverts some air to pushing the marbles even further off line could elevaute this problem. Less marbles on the track would lead to more side by side & wheel to wheel racing. As it is the drivers dont want to go off track to attemt a pass because the marbles gunk up their tires and it then takes thema lap or two to clean them off.

[Ogami musashi]

Hard vs soft is meaningless in compound terminology... and you CAN have stiff compounds that come to temperature very quickly.

Yes of course, the inverse is possible too.

Furthermore I'd say its much easier to grain "soft" tires than "hard."

Disagree, well, if the tyre is a slick, graining will be higher on a hard compound.

I did say tougher, as in more resistant to abuse.

Yes but that's a bit like saying "a lighter, heavy material". Stiffness can be from construction but for a given construction the stiffness is pretty much equal to hardness isn't it?

I'd still say it's much more a compound than construction parameter.

I don't mean the opposite, i just said, just like you say it for graining, that you can have soft, grippy tyres very resistant and friendly in the overshoot.

[Jersey Tom]

Slick tire or not, typically the "softer" or grippier compounds cold tear and grain easier. I haven't seen one race series where this isn't the case. I do work for a tire company Which is why I'm not going to say much...

But no, stiffness is not equal to hardness, even with identical constructions. You can have an A and B with the same stiffness, with much different hardness levels.

Similar concept to steel. Even with the same alloy you can have test piece A and test piece B with the same stiffness, but wildly different hardness levels.

[Ogami musashi]

Slick tire or not, typically the "softer" or grippier compounds cold tear and grain easier. I haven't seen one race series where this isn't the case. I do work for a tire company Which is why I'm not going to say much...

As i'm not tyre expert i'll leave it to you, why is that soft compounds grain easier?

But no, stiffness is not equal to hardness, even with identical constructions. You can have an A and B with the same stiffness, with much different hardness levels.

Similar concept to steel. Even with the same alloy you can have test piece A and test piece B with the same stiffness, but wildly different hardness levels.

Okay there's a little language barrier here, stiffness and hardness in french translate the same, could you please explain the difference in the concepts between the two? thanks.

[Scotracer]

Stiffness is the amount of force it takes to deflect a material by a certain displacement (the more force it takes, the higher the stiffness), otherwise known as the Young's Modulus. The Hardness of a material is how much force a material can take before plastic deformation takes place.

In brief: Stiffness of a material is the hardness of a material in the elastic region (before yield point).

[Jersey Tom]

Dusted off the old Materials Science and Engineering textbook...

Hardness: The measure of a material's resistance to deformation by surface indentation or by abrasion.

Modulus of Elasticity: The ratio of stress to strain when formation is totally elastic; also a measure of the stiffness of a material.

Again using steel as an example, I can have AISI4130 (UNS G41300) and no matter what heat treatment I do, the stiffness is going to be about the same: 200 GPa / 30 Mpsi (roughly). But by changing the microstructure of the material through heat treating I can anneal it down to 95 Rockwell B ("17" Rockwell C) or harden it to probably 40+ Rc.

A "soft" (ie "less hard") material is by definition less resistant to abrasion, and will likely have a lower yield or ultimate strength. "Soft" dry compounds may have higher ultimate grip than a "hard" one, but when you push it past the limit it will likely shred, tear, and grain easily. Harder might not give you as much grip, and you'll find that limit earlier, but they would likely take more abuse.

Of course again, the actual hardness of the rubber compound, as you'd measure with a durometer, doesn't tell you anywhere near the whole story and is often misleading.

Point being is that over the years since the days of Gilles Villeneuve and Rene Arnoux, Bridgestone et all may have progressed to higher grip, "softer", more "on the limit" tire compounds. But if you really go for it and start overdriving the tires, locking them up into braking zones, spinning rears on exit, etc.. they could go off very quickly, and the margin for error would be very small. Tough compounds, or ones that breakaway smoothly, wouldn't give you the ultimate grip level but might encourage drivers to really push the car without having to worry of wadding up the chassis.

Just some ideas. Mostly conjecture.

[Ogami musashi]

Thanks for the definitions, having the same definitions for words is important.

I get your point but would add a nuance to that.

I think the problem is tight. Modern F1 driving is not anymore about driving on the limit, i mean really ON it but rather Close to it. The reason is simple, the average speeds (cornering, accelerating, braking) make any overshoot dramatic in loss of time (and maybe more) so driving evolved towards something very fine and very technical were the faster guy (if we skip the car differencies) is the one that managed to get the closest to the limit.

To do that you need to be very precise and tweak your car balance with a lot of skill but in the recent years drivers complained about the fact the tyres (being grooved) gave away without any warning.

It was not a question of wear but of performance decrease. The problem is that they tend to drive even lower than the limit which is not as interesting.

But the culprit is again in the tyres and to some extent in aerodynamics. The problem is that offer more and more grip (and for some other reasons) the slip angle window of a modern racing tyre is very narrow. the Tyre get's its max Fy at very low slip angles but suddenly lose it when you increase it.

In the opinion of some people in F1, a solution would be to have larger slip angle window for tyres, in this way drivers would be more confident because overshooting the limit would not mean spin and crash but rather be slowed down and that would allow to exploit the modern driving technique required for those fast machines.

But you know what, i think the spectacle far many fans would be less exciting, for the simple fact that this would result in even less noticiable errors.

Let's face it, people want to see pretty apparent driving technics, 60's slides are so popular because it is easy to grasp the cinematics but telling the one who had the more grip in modern F1 is another world.

[Conceptual]

I'm pretty sure that Bridgestone said that the graining in F1 tyres was down to the edges produced by the grooves, and that the slicks will not grain.

So, according to that, it isnt the compound or the construction, it is the edge area that is the culprit of graining.

And less graining means cleaner off-line, thus leading to more passing attempts.

Remember, it is not overtaking that is lacking, it is the number of attempts.

[Jersey Tom]

I'm pretty sure that Bridgestone said that the graining in F1 tyres was down to the edges produced by the grooves, and that the slicks will not grain.

So, according to that, it isnt the compound or the construction, it is the edge area that is the culprit of graining.

Not how it works. Slicks grain up just as easy as grooved tires.

Grooves are a separate issue.