2012 Tyre Temperature & Pressures

[bitbp]

I have no knowledge about tyres at all, hence this thread (and post) asking for advice.

Looking at the link of the theorical right temp for each Pirelly tyre posted by Kalinka. Tyre temp of that run from Fernando were around 30-50ºC below temp depending of wich compound they were. So according of what Mikey_s have said they might not be working properly and then loosing grip. Even when teams heat up tyres to set them up, I guess if the car is not able to heat them (or maybe we should say to keep them on the optimal temp) then the tyres wont be melting the resin and then ti wont be giving max grip.

Also how affects preassure to all this? With my total lack of knowledge I thought higher preassure mean less surface in contact and harder to keep tyre at the right tyre temp.

I thought all this would meant less grip and this would lead to a higher tyre degradation. (Less grip, the car is more "slidey" wich will mean the tyres will "die" sooner)

This was what I thought (and got told also) but JT just destroyed all this...

I would love to learn on this matter so please feel free to correct all the wrong theory.

Thanks.

[Jersey Tom]

Pressure is easy enough to conceptualize with your own car as a reference point.

Let's say you have a Renault Clio with manufacturer recommended tire pressures of 28 psi. If you let air out until they're at 10 psi... is your car now going to handle like a Ferrari F430 and have tons of "grip"? No. It will drive like junk because the tires don't have enough structure to support and work with the load on them.

No different for a race car. If it were as simple as less air = more footprint area = more grip = faster, then all the cars would line up on the grid with nearly flat tires. As with many things in life, there's a balance point of how much air works best for what you're asking of the tires.

Now consider we know that how much load is put on the tires factors into how much air they need. Given how much downforce a F1 car generates, the amount of load - and "best" tire pressure - might be different between T1 and T3, and T8. Which corner do you think is most important? How much downforce do you think you're making? How accurate is your lap simulation as far as how fast you're going to be going in general? Huge question marks there.

Then even if you have a perfect prediction of your speeds and loads, there's the question of tire data. How much does data does Pirelli supply to the teams? Maybe a lot, maybe a little, maybe crap all. We don't know. How good is the data? Maybe it's great, maybe it's junk. We don't know.

All of this leads to uncertainty and grey area. Maybe Ferrari would go faster if they dropped 1 psi. Maybe they go faster if they ADDED 1 psi. Maybe that whole temp / pressure sheet is BS, filled out with nonsense and tossed carelessly for someone else to find (it's been known to happen before).

Temperature is no amount less complicated. Moreso IMO. "Optimum" temperature... I hate the phrase with a passion. Optimum? Optimum for what? Speed over one lap? 10 laps? Maybe heat is your friend, maybe it's your enemy. Does Pirelli know what the "best" temperature is for each of its compounds? I'd say probably not, or certainly not to the degree of precision that many assume. Once you start digging into rubber/track tribology you might find that the "best" temperature for rubber on one type of asphalt is different than another. Even if "hot" gives you lots of limit "grip" it might make the thing feel too soft and "greasy" and slow you down because it's rubbish to drive.

Hope that's helped make things crystal clear

[strad]

So Tom..In reference to all the above wouldn't you agree that the severe limitations on number of tires available and limited track test time has really made it much harder for them to optimize their package as regards tires and suspension?

[Richard]

That can only be a good thing (within reason) for sorting out the men from the boys. The more talented teams will better manage the uncertainty.

[Jersey Tom]

So Tom..In reference to all the above wouldn't you agree that the severe limitations on number of tires available and limited track test time has really made it much harder for them to optimize their package as regards tires and suspension?

Makes them very much reliant on the quality and quantity of data provided by Pirelli (assuming they can't do their own F&M testing).

[Kiril Varbanov]

"The dry 'grooved' tyres used up until very recently were typically designed to function at between 90 degrees Celsius and 110 degrees Celsius." - talking Bridgestone.

[Lurk]

@JT: what F&M does mean?
Speaking quality & quantity of data there is a good example with Renault when they switched from Michelin to Bridgestone. They built a fairly accurate model of Michelin tyres with more than 100 variables & bulk of liable data. When they switched to Bridgestone, the Japaneses gave them a 4 variable model and it was inaccurate. Enstone had to understand these tyres by their own.

BTW do you know how tyre manufacturers process data (those given by the teams) with which they are supposed to develop tyre? Since some teams (maybe even all) give to them slightly modified to fanciful values, how they manage to filter these data to develop a proper product?

[Jersey Tom]

@JT: what F&M does mean?

Force and moment.

BTW do you know how tyre manufacturers process data (those given by the teams) with which they are supposed to develop tyre? Since some teams (maybe even all) give to them slightly modified to fanciful values, how they manage to filter these data to develop a proper product?

It's not easy, I'll tell ya that.

[bitbp]

Pressure is easy enough to conceptualize with your own car as a reference point.

Let's say you have a Renault Clio with manufacturer recommended tire pressures of 28 psi. If you let air out until they're at 10 psi... is your car now going to handle like a Ferrari F430 and have tons of "grip"? No. It will drive like junk because the tires don't have enough structure to support and work with the load on them.

No different for a race car. If it were as simple as less air = more footprint area = more grip = faster, then all the cars would line up on the grid with nearly flat tires. As with many things in life, there's a balance point of how much air works best for what you're asking of the tires.

Now consider we know that how much load is put on the tires factors into how much air they need. Given how much downforce a F1 car generates, the amount of load - and "best" tire pressure - might be different between T1 and T3, and T8. Which corner do you think is most important? How much downforce do you think you're making? How accurate is your lap simulation as far as how fast you're going to be going in general? Huge question marks there.

Then even if you have a perfect prediction of your speeds and loads, there's the question of tire data. How much does data does Pirelli supply to the teams? Maybe a lot, maybe a little, maybe crap all. We don't know. How good is the data? Maybe it's great, maybe it's junk. We don't know.

All of this leads to uncertainty and grey area. Maybe Ferrari would go faster if they dropped 1 psi. Maybe they go faster if they ADDED 1 psi. Maybe that whole temp / pressure sheet is BS, filled out with nonsense and tossed carelessly for someone else to find (it's been known to happen before).

Temperature is no amount less complicated. Moreso IMO. "Optimum" temperature... I hate the phrase with a passion. Optimum? Optimum for what? Speed over one lap? 10 laps? Maybe heat is your friend, maybe it's your enemy. Does Pirelli know what the "best" temperature is for each of its compounds? I'd say probably not, or certainly not to the degree of precision that many assume. Once you start digging into rubber/track tribology you might find that the "best" temperature for rubber on one type of asphalt is different than another. Even if "hot" gives you lots of limit "grip" it might make the thing feel too soft and "greasy" and slow you down because it's rubbish to drive.

Hope that's helped make things crystal clear

Crystaline as water Thanks a lot.

[GrizzleBoy]

Temperature is no amount less complicated. Moreso IMO. "Optimum" temperature... I hate the phrase with a passion. Optimum? Optimum for what? Speed over one lap? 10 laps? Maybe heat is your friend, maybe it's your enemy. Does Pirelli know what the "best" temperature is for each of its compounds? I'd say probably not, or certainly not to the degree of precision that many assume. Once you start digging into rubber/track tribology you might find that the "best" temperature for rubber on one type of asphalt is different than another. Even if "hot" gives you lots of limit "grip" it might make the thing feel too soft and "greasy" and slow you down because it's rubbish to drive.

Which is precisely why Pirelli assign different compounds to different tracks, in order to retain their optimum operating temperature

Different track abrasiveness = different amounts of heat they put into the tyres = tyre compounds are matched to said abrasiveness to give optimum operating temperature under use.

Monza an its new surface gets the super softs as option tyre due to its low abrasiveness (or even "slipperyness" as it has been called).

Melbourne will be assigned soft tyres as the track is obviously more taxing on the tyres.

And does Pirelli know the "best" temperatures for their tyres?

Who knows, but they know at what temperature they begin to transform into what the drivers need for grip without degrading too fast as they will obviously have done tests with the test car at the very least and this is what they tell us.

[Richard]

Grizzle - The idea of an optimum temp is a myth because as you say it is dependent on external factors such as the track texture, race duration versus quali, etc.

[munks]

And further than that, since rubber friction is related to a combination of speed and temperature (yes, a *combination*, whose effects can NOT be separated), the so-called "optimum temperature" is different for every corner. In fact, it's different for different parts of a single corner (the dynamics in the footprint are different between braking, cornering, accelerating, and combinations of them). And furthermore, since the surface temperature changes quickly during a single corner, you can't possibly have it "optimal" through the whole thing.

Now throw in other conditions, like how the heat cycles have affected the rubber properties. Or how much dust, rubber, or various lubricants are on the track, all of which can affect the temperature at which the tire will work best (which, as JT pointed out, is not always where it produces the most grip). There's simply no clearly-defined optimum operating temperature.

[ubrben]

Monza an its new surface gets the super softs as option tyre due to its low abrasiveness (or even "slipperyness" as it has been called).

Or because it's a low frictional energy per km track regardless of track surface...

hat can only be a good thing (within reason) for sorting out the men from the boys. The more talented teams will better manage the uncertainty.

Race Engineering generally is about having a good physical understanding of how the car, tyres, etc "work" but being more than pragmatic about the degree to which you can quantify them.

As a general point (that I've made before) the people on this (or any BB) who aren't involved in racing are very naive about the extent to which there is one right answer or the extent to which you can quantify things.

I just had a pretty decent weekend at a pretty big race. Can I "calculate" the "optimum tyre temperature"? Categorically not. Can I determine what concept of rubber I need if it gets hotter, track rougher, etc? Yes.

The rules of physics don't change, but there's just never enough data to make a completely informed choice. This is why race engineering is as much a sporting activity as it is a technical one, and why it's so damn rewarding when you get it right:

Art without engineering is dreaming. Engineering without art is calculating.
Steven K. Roberts

Ben

[ubrben]

Incidentally there is a lot of calculating and virtually no art in F1 design and race engineering. That's why you get GP2 cars out-qualifying back grid F1 cars at Monaco and teams like Ferrari, who should know better, getting it as wrong as they have this year.

Ben

[SeijaKessen]

Very interesting thread.

Had a question regarding the Pirelli tires.

Is the tire pressure and grip the same, less, or greater, than any of the prior manufacturers like Bridgestone or Goodyear?

Did teams run higher tire pressure in the past versus now?