How stiff are F1 tyres?

[sdimm]

Hi,

I was just wondering if anyone knows how stiff the slick F1 tires are when pumped up with the right pressures. So how much of a spring effect do they have in Newton/mm?
Maybe someone can give an estimate or perhaps from some other tire.

//Happy Swede

[WhiteBlue]

I cannot put a figure to it but it is clear that the 2010 front tyre will be massively stiffer than the 2009 version.

At a maximum load of more than half a metric ton they only give a few mm. That could give you an approximation.

[Jersey Tom]

"The right pressures" is pretty vague.

[xpensive]

I guess the deflection comes two different components, the pressure-dependent geometrical size of the contact-patch, and the non pressure-dependent wall-stiffness. But as for a number, I don't have a clue, scarbs?

[sdimm]

"The right pressures" is pretty vague.

Does it matter? I don´t know what pressures they use but I´m still looking for the actual stiffness of the tire as it is when they are using it and not when it´s without any pressure at all.

[Scuderia_Russ]

"The right pressures" is pretty vague.

Does it matter?

Very much so. He can't give you an answer otherwise.

[xpensive]

You know what, here in Sweden we'd be mighty happy with a ballpark figure for a typical pressure, say 400 kPa?

[Jersey Tom]

Would also help to know.. what are you trying to use this for?

Tire stiffness changes with inflation pressure, load, camber, slip angle...

[mep]

Tyre pressure should be something around 1,4 bar.
F1 tyres are quite thick (on diameter) compared to other racing tyres so they should have relatively hard shoulders. Especially to prevent to much sideway deflection during cornering with high g loads.
In contrast a drag racing tyre can have softer shoulders because it doesn’t experience much lateral loads.
I think this thick rubber layer is rather old fashioned for cars with high lateral loads. They just look like that because some odd rule defines it.

Of course that’s just what I think and what makes sense to me.

[newbie]

I believe the standard tyre pressure is around 18 PSI

for vertical stiffness you can assume between 20 and 30 mm of deflection (at the hub) when 6 kN of force is applied. relationship is roughly linear.

[xpensive]

I believe the standard tyre pressure is around 18 PSI

for vertical stiffness you can assume between 20 and 30 mm of deflection (at the hub) when 6 kN of force is applied. relationship is roughly linear.

18 psi, that's only 125 kPa, are you sure about this?

[WhiteBlue]

for vertical stiffness you can assume between 20 and 30 mm of deflection (at the hub) when 6 kN of force is applied. relationship is roughly linear.

An inch of tyre deflection sounds an aweful lot for an F1 car. They have very little ride height and the suspension will also travel some which should be in the same magnitude as the tyres.

[mep]

for vertical stiffness you can assume between 20 and 30 mm of deflection (at the hub) when 6 kN of force is applied. relationship is roughly linear.

Way to much for just 6kN.
Where do you have those figures from?

[Jersey Tom]

for vertical stiffness you can assume between 20 and 30 mm of deflection (at the hub) when 6 kN of force is applied. relationship is roughly linear.

Way to much for just 6kN.
Where do you have those figures from?

Sounds reasonable to me, both the spring-rate and inflation (18-22psi).

[xpensive]

Very simplified, but a start;
- A vertical load of 6 kN and a pressure of 130 kPa (19 psi), would indicate a contact-patch of 45 000 mm^2.
- An area of 45 000 and a contact-patch width of 300 mm, means a patch-length of 150 mm.
- A patch-length of 150 and a tyre-radius of 330, suggests a geometrical deflection of about 9 mm.
- Remaining deflection from tyre-wall.

Does this come across as at all reasonable?