How stiff are F1 tyres?

[WhiteBlue]

I would then conclude that we were at 300 N/mm in 2009. Not so much difference to 350.

I understand why you said that. However, the difference would be equivalent to an increase in pressure of around 6 psi (0.4 bar). You might like to try that change on a road car (for a short time & on a strictly experimental basis). I imagine the effect would be quite noticeable, even subjectively. Then think (but only think) about the effect of doubling the stiffness....

There is no reason why the recommended tyre pressures should not decrease to compensate the effect from the tyre shape. In fact that could be the first thing they may not keep equal. It is something that probably can be verified during the season.

[xpensive]

So very you WB, to only engage in a technical thread if the topic leaves enough room for speculation and opinions.

[WhiteBlue]

So very you WB, to only engage in a technical thread if the topic leaves enough room for speculation and opinions.

It is a difficult issue. I haven't made up my mind what is going to model the tyre behavior closest to reality. It looks like DaveW is pretty competent on the issue. So I'm taking clues from his posts. Honestly I don't know what the physical properties of this years tyres are going to be. I can only apply mechanical analysis to the data that are published. I have no access to team tyre data at all. So in reality we will have to watch this season unfold and take our conclusions from whatever gets published.

[WhiteBlue]

AMuS have solved a riddle that provided much discussion here on F1technical earlier in the year. I have shown by comparative mechanical analysis that the 2010 front tyres are much stiffer than the 2009 tyres. A number of "experts" have called me wrong but it turns out that an independent source now confirms my result.

Bridgestone liefert neue Reifenkonstruktion
Der Unterschied zu den Vorjahresreifen liegt in der Konstruktion. Die Karkasse ist wesentlich steifer geworden. Der Hinterreifen ist ein Ableger jenes Reifentyps, den Bridgestone 2005 als Ersatz für den GP USA in Indianapolis mitnahm. Damals haben die Japaner aus Angst vor der Steilkurve eine extrem steife Konstruktion gewählt.

Bridgestone supplies new tyre construction
The difference to last year's tyres is the construction. The carcass has become substantially stiffer. The rear tyre is an evolution of the one that Bridgestone took to Indianapolis in 2005 as a replacement for the USGP. At that time the Japanese had selected an extremely stiff construction for fear of the banked corner.

After discussions I have estimated the increase in stiffness to be somewhere between 20 and 50%. Substantially stiffer sounds like I have not been wrong in my estimate.

I'm still in doubt about the relative stiffness of rears and fronts. DaveW suggested that Bridgestone would want the fronts to be less stiff than the rears which isn't possible with the same construction reduced by a few millimeters of width. If Bridgestone actually did what DaveW thought they would do they must have used an even more rigid construction for the rears than they showed in the picture.

The AMuS story suitably explains why a number of teams and drivers struggle with heating their tyres and why it becomes more difficult to do with low fuel. With considerably stiffer tyres you need higher inertial forces under lateral and longitudinal acceleration to generate the heat in the tyres. With the higher weight of the fuel load that isn't a problem because cars will have 110 kg more mass. In qualifying that higher mass is missing and and you have to find other means to generate the squash which heats up the tyres.

[mep]

I think they choose the worst tire they could get.
During 2005 the tires had to last the whole race and had additional loading on US GP. No wonder these tires last a whole race now again and give us a lack of action during the race.
I have been blaming the tires since the season started.
viewtopic.php?f=6&t=8244

On Canadian GP we saw tires who wore out quite fast and you see it was a super race.

[marcush.]

I think they choose the worst tire they could get.
During 2005 the tires had to last the whole race and had additional loading on US GP. No wonder these tires last a whole race now again and give us a lack of action during the race.
I have been blaming the tires since the season started.
viewtopic.php?f=6&t=8244

On Canadian GP we saw tires who wore out quite fast and you see it was a super race.

Now we start to see what could have been .Still the tyre carcass seems to be too stiff for some chassis /drivers and they just wear the compound instead of working the tyre it looks like ? In Canada not even the primes would last in the first laps.
The question is then ,why start on primes when they won´t last any longer than option.the tyres keep being a mystery this year more than in 2009..

[WhiteBlue]

marcush, the Montreal tyre situation was absolutely consistent with the diagnosis of a carcass with too much stiffness compared to the extremely slippery asphalt. The tyres develop no grip that enables them to generate internal heat. The slip causes contact layer over heating and graining.

[marcush.]

marcush, the Montreal tyre situation was absolutely consistent with the diagnosis of a carcass with too much stiffness compared to the extremely slippery asphalt. The tyres develop no grip that enables them to generate internal heat. The slip causes contact layer over heating and graining.

you are of course right..I wanted to say those tyres are a mystery not to us but
to Mercedes,Ferrari,Schumacher ,Vettel,Alonso and Massa..

[Jersey Tom]

Definitely gettin a kick out of these assessments...

[mx_tifoso]

Definitely gettin a kick out of these assessments...

Why not answer the question or help everyone else understand the subject instead of posting that sort of comment?

Not everyone is a tire engineer you know.

[marcush.]

I can live with this mx..
my comments are meant to be at least a bit ironic ,mind you..I´m well aware that I don´t understand F1 tyres .But I can live very well with this ,knowing that a lot of people working with them do not understand them as well.. or at least draw questionable conclusions out of their knowledge..

[WhiteBlue]

The main point for me is to understand the few bits that get published about the F1 tyres. When Bridgestone published the contour of the 2009 and the 2010 front carcass it was obvious that the all other things being equal the new front tyre would be much stiffer.

The publication in AMuS confirmed that and added the information that the rear tyres also had been given additional stiffness, obviously with the intention to improve the safety for the increased running weight of the cars.

The thing that I'm not understanding is why certain cars and drivers have more problems to get heat into the stiffer tyres than others. The obvious candidates being Massa at Ferrari and Schumacher at Mercedes. The Red Bulls and McLaren drivers do not seem to have this problem being more "aggressive" with their tyres. I wonder what is making the difference. Both cars are probably having the highest down force in corners right now. Red Bull due to generating most of it by the diffusor and bodywork and McLaren due to more wing angle which is neutralized on the straight by the F-duct.

It looks like the teams were not fully understanding the changes in tyres either this year. Mercedes spend several month reworking their weight distribution following the tyre changes.

[ubrben]

I can just about accept that you can infer a stiffness change based on only having the tyre profile assuming that the construction stays the same.

However the profile is one tiny part of information - it simply isn't enough to know for sure. You have no info on plies, fillers, bead, breakers, overlay, etc to know anything for sure.

Sorry to be negative, but sometimes in engineering you need to realise when you don't have adequate data...

BTW I'd bet my house that the new front isn't 600N/mm

Ben

[mep]

The question is then ,why start on primes when they won´t last any longer than option.the tyres keep being a mystery this year more than in 2009.

Yea it's really a myth for my why most of the teams started on hard tires last GP.
Even the commentators all agreed that McLaren will fail because they started on soft ones.
Well I think the opposite is true.
When you have a good and a bad tire you should start the race with the bad one.
Especially when you are leading the race and therefore set the pace for the following cars.
With the soft tire:
1. you are better in qualy
2. you are better at the start
3. a safety car is more likely at the start of the race so you can get rid of the shitty tire in a easy fashion
4. when the tire starts to get worn out the following cars can't use their tires because they have to follow you.
5. when you can't hold up the other cars any longer you go to pit, after that you have fresh hard tires and an advantage against the used ones of your competitors
6.when there is a safety car later in the race, the gap to the other cars is closed but they still have to pit and take the bad tires.
7. how should your competitors fight against you in the end of the race when their tires are slower after some laps?

I guess the teams hopped the soft tire will improve at the end when there is more rubber on track but obviously this effect is not big enough.

[Jersey Tom]

Definitely gettin a kick out of these assessments...

Why not answer the question or help everyone else understand the subject instead of posting that sort of comment?

Not everyone is a tire engineer you know.

Can't answer the question because there's just about no information to go off. Same as what Ben is getting at. Saying that the tires are 20-50% stiffer is rampant shot-in-the-dark speculation (50% is a huuuge number).

Then going on to say that the extra stiffness (presuming the report is even accurate) is why team X is having a hard time generating heat compared to team Y is a big stretch.

Plus who is to say what direction the tire is stiffer? Stiffer vertically? Is it softer tangentially? Laterally? Torsionally?

Does the "stiffer" carcass mean teams have to run less air pressure, which then winds up generating equivalent amounts of strain and heat buildup?

Does the "stiffer" carcass mean you have a smaller, more focused footprint with higher energy which will generate more surface heat?

There's a dozen ways you could go with this, all equally silly.