How stiff are F1 tyres?

[mep]

speedsense
Tires are the holy grail when it comes to suspension design and setup.

Can you explain how the tires affects your suspension design?
I mean most parameters like chamber, toe,... are designed to be adjustable anyway.
I have read trough Milkens race car vehicle dynamics but can't find a prober answer on this.
The parameters where I understand the importantce to define them on average are center of gravity / center of downforce, but these are no specific suspension design parameters. I would rather call them general car parameters.



One thing I miss in this threat is nobody is talking about slip angles.
When you change the stiffness of the tire carcas then first of all you are changing the slip angle where your tire provides max. grip.
Remember the slip angle is somehow a value of how much your tire deforms under a given force.
So stiff carcas = low slip angle, weak carcas = high slip angle for the same lateral force.
Now I can imagine it’s possible that your front and rear tires don't match regarding their slip angles.

Like when you have a very hard rear tire and a very soft front tire you must steer harder to get the maximum grip out of your front tires. This should give you a feeling of understeer.
Another scenario is when you have a very soft rear and very hard front.
You might be unable to produce the needed slip on the rear without overworking your fronts. So you feel a lack of rear end grip.
On the other hand you have something left you can use for propelling your car so it might feel got when you accelerate out of corners.

In the end shouldn’t be there something like a center of slip?
A point where front and rear slip is equal under a given driving condition regarding the tires you use.
When you have such a point you can define its location regarding the position of your center of gravity and center of downforce.

[Belatti]

So you end up doing what I and many people in junior/local series use to do when you dont really master the thing your working on:

Measure everything that you are able to, with the most reliable method you can imagine and when you have any problem, see if some of the measured parameters has changed.

Then if you apply the scientific method, you [-o< and you have luck, you might learn something.

[JohnsonsEvilTwin]

Tyres are the single most important factor in F1.
My grandfather worked in the tyre retread business and said it back when I was wee nipper in the 80s, and I know exactly what he means.

If you have the fastest car with amazing fantastical aero but the car cannot use the grip given up by the tyre, you will finish behind a car thats average but uses its tyres well.

When you think of the contact patches and how important it is for the car to
a) change direction
b) move forward
c) stop
all this things have one thing in common, it requires tires.
The rest follows....

[mep]

We don't need to question their importance here point out how it affects the design of the car.

[RacingManiac]

We don't need to question their importance here point out how it affects the design of the car.

While a lot of those parameters are adjustable statically, how they change as the suspension move in dynamic fashion, and how the load is transferred to them is based on your design of the whole system. Ideally if you know what the tire likes you'll design your suspension to suit the tire's need.....

[WhiteBlue]

One thing I miss in this threat is nobody is talking about slip angles.
When you change the stiffness of the tire carcas then first of all you are changing the slip angle where your tire provides max. grip.
Remember the slip angle is somehow a value of how much your tire deforms under a given force.
So stiff carcas = low slip angle, weak carcas = high slip angle for the same lateral force.
Now I can imagine it’s possible that your front and rear tires don't match regarding their slip angles.

+1

This is exactly the kind of discussion I had hoped we would get from more learned tyre experts. We are seeing consequences of the stiffer carcass design and they are not being explained.

Prior to the confirmation from AMuS some people even denied that the tyres had become much stiffer for 2010.

I'm still waiting for an explanation why Red Bull and McLaren have less problems than Ferrari and Mercedes. Is it just more downforce?

[ubrben]

Have you got a reference for the 2010 tyre being stiffer?

There isn't enough data to clearly say why one team is easier on its tyres than another. So many factors are involved. Damping is one area where you can dramatically alter the amojnt of energy dissipated in the tyres, but again there's no data so I can't draw any definitive conclusions.

Ben

[ubrben]

speedsense
Tires are the holy grail when it comes to suspension design and setup.

Can you explain how the tires affects your suspension design?
I mean most parameters like chamber, toe,... are designed to be adjustable anyway.
I have read trough Milkens race car vehicle dynamics but can't find a prober answer on this.
The parameters where I understand the importantce to define them on average are center of gravity / center of downforce, but these are no specific suspension design parameters. I would rather call them general car parameters.



One thing I miss in this threat is nobody is talking about slip angles.
When you change the stiffness of the tire carcas then first of all you are changing the slip angle where your tire provides max. grip.
Remember the slip angle is somehow a value of how much your tire deforms under a given force.
So stiff carcas = low slip angle, weak carcas = high slip angle for the same lateral force.
Now I can imagine it’s possible that your front and rear tires don't match regarding their slip angles.

Like when you have a very hard rear tire and a very soft front tire you must steer harder to get the maximum grip out of your front tires. This should give you a feeling of understeer.
Another scenario is when you have a very soft rear and very hard front.
You might be unable to produce the needed slip on the rear without overworking your fronts. So you feel a lack of rear end grip.
On the other hand you have something left you can use for propelling your car so it might feel got when you accelerate out of corners.

In the end shouldn’t be there something like a center of slip?
A point where front and rear slip is equal under a given driving condition regarding the tires you use.
When you have such a point you can define its location regarding the position of your center of gravity and center of downforce.

The Milliken Moment Method outlined in Cpt 8 of RCVD will tell you where your weight distribution and aero balance should be for a given front and rear tyre package.

Also your stiff carcass / weak carcass conclusion are excessive generalisations. I just put a 10% softer vertical construction on the front of a GT car, but I made the tread belt more torsioanlly stiff. Massive turn-in grip with a softer case...

Problem is that you have vertical stiffness, lateral stiffness and torsional stiffness of the belt. They're all to a degree tunable with some independance of each other, meaning it's not as simple as you make out.

Ben

[speedsense]

The study of rubber bands.....no one simple solution. Is this case,rubber bands with wheels, suspension attached...no multiple simple solution...especially when you can alter the size/strength of the rubber band with air (nitrogen) pressure.. or wheel size....

[marcush.]

has anyone read the 3part feature over Tyres from pat smmonds in Race Tech ?

I stumbled accidentially over it this week ,but only got hold of the last part of it ..it seems quite an interesting bit...

[DaveW]

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.

Interesting quote that appears to acknowledge that Firestone/IRL experience was taken on board by Bridgestone for the infamous 2005 USGP.

Ubrben's house is fairly safe, BTW...

[ubrben]

Thanks Dave

Seriously rear GT tyres on 18" rims aren't 600N/mm so an F1 front certainly won't be.

If there's solid evidence they've increased stiffness fine, but even then it's impossible to know how this has influenced the design of the car without any tyre data.

You can't even generalise about the effect of a stiff tyre anyway without knowledge of the compound. Bridgestone run very stiff rear constructions in MotoGP, in this case to work a very stiff compound.

Ben

[strad]

How stiff are F1 tires? Not at all. I lost the clip I made, but I used to have a video off a Speed channel show that showed the host literally wad up one of the old grooved F1 tires.

[speedsense]

How stiff are F1 tires? Not at all. I lost the clip I made, but I used to have a video off a Speed channel show that showed the host literally wad up one of the old grooved F1 tires.

Was it on a rim and inflated with air? ...now that I would like to see...

Carbon fiber isn't stiff at all until epoxy is applied....

[strad]

Was it on a rim and inflated with air? ...now that I would like to see...

Carbon fiber isn't stiff at all until epoxy is applied....

What ya smokin? I'm talking about the tire alone by itself..The guy could just wad it up ...one ply shìt that.
Carbon fiber is basically laid up like fiberglass