2014 tyre supplier decided ?

[timbo]

Just to clarify things here, would 17 inch rims mean a larger tyre diameter as well, or just a much lower profile?

The quote says it's lower profile.

[WhiteBlue]

Just to clarify things here, would 17 inch rims mean a larger tyre diameter as well, or just a much lower profile?

Difficult to say. IMO if they consider to go away from the current diameter of the tyre in order to increase the contact patch there is immediately the question of a different rim diameter involved. But they could keep the contact patch and go for a low profile as an alternative way to get a stronger side wall and shoulder design. There are many different things involved here. The torque change, the safety aspect of potentially heavier wheels, the change in chassis and suspension necessary for bigger dia rims and the political crap.

[xpensive]

If they retain the tyre diameter and reduce the sidewalls by 2 inches, that would probably mean we will have suspensions back?

[bhall]

Just to clarify things here, would 17 inch rims mean a larger tyre diameter as well, or just a much lower profile?

Difficult to say. IMO if they consider to go away from the current diameter of the tyre in order to increase the contact patch there is immediately the question of a different rim diameter involved.
[...]

How would a larger diameter tire increase the size of the contact patch? Doesn't a wider tire make much more sense?

[SectorOne]

Make it extreme. a Caterpillar tire vs a tire on a shopping cart. It´s easy to see that even if we discount width, the caterpillar has a bigger tire patch longitudinally.

But yes, making the tire wider is probably more beneficial.

[raymondu999]

Make it extreme. a Caterpillar tire vs a tire on a shopping cart. It´s easy to see that even if we discount width, the caterpillar has a bigger tire patch longitudinally.

But yes, making the tire wider is probably more beneficial.

Except a caterpillar isn't pneumatic, which of course changes a lot of dynamics. A caterpillar is a belt, not a tyre. Nor would I consider it analogous to one

[WhiteBlue]

Just to clarify things here, would 17 inch rims mean a larger tyre diameter as well, or just a much lower profile?

Difficult to say. IMO if they consider to go away from the current diameter of the tyre in order to increase the contact patch there is immediately the question of a different rim diameter involved.
[...]

How would a larger diameter tire increase the size of the contact patch? Doesn't a wider tire make much more sense?

Good point. In an ideal world without deformation there would not be a contact patch but only a line. Then a bigger tyre diameter would not produce a bigger contact line but you have to consider that there is deformation involved. I guess that a bigger diameter tyre would via deformation produce a longer contact patch. Pirelli have actually asked for wider tyres and bigger tyre diameters. Reportedly the teams are even more adverse to diameter changes than they are to width changes. But that is just reflecting their internal development strategy and their time and their resource constraints. From a pure technical point of view the tyre companies are probably right to ask for dimensional changes particularly concerning the rim diameters. Wider rear tyres would be more draggy. Bigger diameters as well but less so. So from an aerodynamic point of view keeping the outer dimensions with a lower profile for more strength would be the best for performance.

[SectorOne]

Make it extreme. a Caterpillar tire vs a tire on a shopping cart. It´s easy to see that even if we discount width, the caterpillar has a bigger tire patch longitudinally.

But yes, making the tire wider is probably more beneficial.

Except a caterpillar isn't pneumatic, which of course changes a lot of dynamics. A caterpillar is a belt, not a tyre. Nor would I consider it analogous to one

This is a caterpillar.


It doesn´t matter what you take, you can take a ping pong ball and a football and come to the same conclusion that a bigger circle (in this case you have to see the ping pong ball and football as 2D objects) will have a bigger contact patch.

We can even use the picture here to come to the conclusion that a bigger diameter will provide a bigger longitudinal contact patch.

Edit: It´s the same as making a wider tire, increaseing the lateral contact patch. except it´s longitudinal.

[timbo]

Good point. In an ideal world without deformation there would not be a contact patch but only a line. Then a bigger tyre diameter would not produce a bigger contact line but you have to consider that there is deformation involved. I guess that a bigger diameter tyre would via deformation produce a longer contact patch.

Probably that would primarily affect longitudinal grip, while lateral grip change would not be as big.

[xxChrisxx]

Make it extreme. a Caterpillar tire vs a tire on a shopping cart. It´s easy to see that even if we discount width, the caterpillar has a bigger tire patch longitudinally.

You are attributing a seen phenomena to the wrong thing. It's primary cause is not size, it's the relative stiffness and load.
It's easy to make small tyres stiff and small things tend to be light.

[WhiteBlue]

Good point. In an ideal world without deformation there would not be a contact patch but only a line. Then a bigger tyre diameter would not produce a bigger contact line but you have to consider that there is deformation involved. I guess that a bigger diameter tyre would via deformation produce a longer contact patch.

Probably that would primarily affect longitudinal grip, while lateral grip change would not be as big.

I don't think so. The grip depends of the area and not the length the area has in the direction of the force. Directional differences in grip are probably much more a consequence of construction and the deformation due to construction differences.

[SectorOne]

Make it extreme. a Caterpillar tire vs a tire on a shopping cart. It´s easy to see that even if we discount width, the caterpillar has a bigger tire patch longitudinally.

You are attributing a seen phenomena to the wrong thing. It's primary cause is not size, it's the relative stiffness and load.
It's easy to make small tyres stiff and small things tend to be light.

Even if you make a tire out of granit then blow it up to twice the size it would still have more granite hitting the ground.

In the exact same way: if you make it wider, you will increase the contact patch.

[raymondu999]

Make it extreme. a Caterpillar tire vs a tire on a shopping cart. It´s easy to see that even if we discount width, the caterpillar has a bigger tire patch longitudinally.

But yes, making the tire wider is probably more beneficial.

Except a caterpillar isn't pneumatic, which of course changes a lot of dynamics. A caterpillar is a belt, not a tyre. Nor would I consider it analogous to one

This is a caterpillar.
http://t3.gstatic.com/images?q=tbn:ANd9 ... 6zV9FsOGVU

No, that's not. That's a caterpillar-branded heavy vehicle - though I understand that in some regions (including yours) you might refer to them as "Caterpillars" - and give you the benefit of the doubt on that. (similarly, my country calls any and all mopeds/scooters "Vespas")

However, in the English language, in fact...

Caterpillar - an articulated steel band passing round the wheels of a vehicle for travel on rough ground.

ie, these:


I can see where we had the misunderstanding, but please do understand that given the proper definition of a caterpillar, how your comment would easily be misconstrued by a large majority of people.

Having said that, we cannot use your example as proof for the reasons stated above by Chris. The increased contact patch (or apparent contact patch) is not a function of the tyre being larger in and of itself.

If you put a 10kg mass on a bicycle tyre, or put it on a caterpillar tyre - which would have a bigger contact patch? If only the tyre diameter changed, with tyre pressures, and all the different masses identical - then the contact patch would be of identical size, because Pressure = Force/Area, and you'd have to exert the same force to hold everything up. Therefore if Force is the same, and pressure is the same, then it goes to follow that the area over which that pressure works is the same.

[Blanchimont]

Tyre patch size depends on the diameter, width, pressure, tyre volume, stiffness of the tyre (which can change with the load and the camber applied), temperature (influencing pressure) and weight of the car. I think these are the main factors to look at when discussing the patch.

[WhiteBlue]

If they retain the tyre diameter and reduce the sidewalls by 2 inches, that would probably mean we will have suspensions back?

Yes, it would take travel away from the tyres and add it to the suspension. It would affect the space they have for brakes, it would change the mass and mass distribution of the wheels, the aerodynamics of the air going through the front wheels and a bunch of other things. I would not be surprised if F1 eventually changes to bigger rims for front and rear in a different year. The rear tyres are obviously more critical and the front tyres may initially stay to minimize the change.