F1 tyre profile

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.

Post Mon Oct 29, 2007 10:31 pm

What's the reason for F1 tyres to have such a high profile i.e. a large outer diameter compared to inner diameter? I know it's because the regulations dictate the dimensions, but why are the regulations as such? It seems to me that the dynamics of the car can be controlled and adjusted much easier with lower profile tyres, as tyres effectively act as an undamped spring and the larger the profile the less control you have over their behaviour. Surely suspension sutups would be much more accurate if you can minimise the movement in the tyre?
williamssam
 
Joined: 12 Oct 2005
Location: Stamford, England

Post Wed Oct 31, 2007 2:46 pm

Is there anyone out there who has an idea?! I've trawled the internet looking for an answer but can't find anything, even this interview with Hisao Suganuma does't offer a full explaination
http://www.f1nutter.co.uk/tech/qa_suganuma.php
williamssam
 
Joined: 12 Oct 2005
Location: Stamford, England

Post Wed Oct 31, 2007 3:15 pm

Well I may be way off on this one, but with formula 1 engines as high-strung as they are a larger diameter wheel would result in significant torque loss as you increase the rolling mass as well as the position of this mass relative to the hub. One would think that an engine with as little displacement (and torque I would assume) would be especially sensitive to this type of loss as the motor has to be running at such high speeds to make peak power. But my theory says nothing about cars of earlier generations were displacement was at less of a premium.

Thoughts,.... ? like I said before I could be missing the point completely, however this does seem logical to me.
“It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so" - Mark Twain
jwielage
 
Joined: 1 Mar 2007
Location: New York City

Post Wed Oct 31, 2007 3:33 pm

I think they have to fit small 13" rims to be forced to use little diameter brake rotors, otherwise with 18" or so they could fit larger brake discs and brake like hell (=more than now) (remember that super braking is one of the main reasons why there is so little of overtaking in F1...)
vis
 
Joined: 16 Jun 2006
Location: Monza

Post Wed Oct 31, 2007 4:48 pm

rkn
 
Joined: 26 Jun 2006

Post Wed Oct 31, 2007 5:35 pm

rkn, thanks for the link to that thread. There was definitely some quality information in there. I would love to see those pictures of tire loadings through Aue Rouge.
“It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so" - Mark Twain
jwielage
 
Joined: 1 Mar 2007
Location: New York City

Post Thu Nov 01, 2007 2:33 pm

Cheers rkn, makes for interesting reading, yet there still doesn't seem to be a definitive answer. Maybe there isn't a technical reason and the regulations have just been this way since the days when high profile tyres were the norm.
williamssam
 
Joined: 12 Oct 2005
Location: Stamford, England

Post Thu Nov 01, 2007 4:13 pm

1)
vis wrote:I think they have to fit small 13" rims to be forced to use little diameter brake rotors, otherwise with 18" or so they could fit larger brake discs and brake like hell (=more than now) (remember that super braking is one of the main reasons why there is so little of overtaking in F1...)


Braking is limited by grip between tyre and ground and varies with speed.
You could put a 18" rotor and brake in the same distance as now, cause wheel would lock.

2)
This quote is from the linked thread above:
While low profile tires would most likely provide a handling benefit they do suffer in one important way .. their lack of ability to store torque windup makes them easy to spin under throttle. Hence, if allowed F1 teams and tire mfrs would likely use low profile tires on the front but maintain tall sidewalls on the rear.


I know what is this guy speaking about, I first saw the effect in a music video (Metallica - Fuel) and then in a TV commercial (I don´t remember wich)
In the Metallica video you see a big black yankee supercharged car accelerating and the traction tyre profile (casually very high) is showed with low speed camera, the wrinkles in the rubber are huge!
Maybe some could post a link to that video and enjoy some Rock and Roll! :D 8) :wink:
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio

"I have no idols. I admire work, dedication and competence." -Ayrton Senna
Belatti
 
Joined: 10 Jul 2007
Location: Argentina

Post Thu Nov 01, 2007 4:25 pm

EDIT: I found from F1 2007 technical regulations that specifies profile:

12.4 Wheel dimensions:
12.4.2 Complete wheel diameter must not exceed 660mm when
fitted with dry-weather tyres or 670mm when fitted with wet-weather
tyres.
12.4.4 Wheel bead diameter must lie between 328 and 332mm.
"You need great passion, because everything you do with great pleasure, you do well." -Juan Manuel Fangio

"I have no idols. I admire work, dedication and competence." -Ayrton Senna
Belatti
 
Joined: 10 Jul 2007
Location: Argentina

Post Thu Nov 01, 2007 8:45 pm

DaveKillens
 
Joined: 20 Jan 2005

Post Thu Nov 01, 2007 9:01 pm

Well, from the top of my head, I think that in an F1 car tyres are an important part of the suspension. Truly, F1 drivers have *sses of steel, or so I've heard... :) Anyway, the higher wall allows the tyre to adsorb larger bumps, like kerbs or the occasional marshall you can run over.

If the tyre takes part of displacement caused by the irregularities on the road, you can use a smaller suspension vertical displacement, in the A-arms. In turn, this could mean that you can use a slightly lower body, closer to the ground, so you get higher downforce, but it is just a thought.

Another effect is notorious in dragsters, where you really can see the tyres wrinkle as they twist around themselves, as Belatti points out, providing you with a sort of a "second" clutch.

Image

On the other hand, the higher the tyre, the more it stretches because of centrifugal force. This means you can attain slightly higher speeds, as the tyre "inflates" at high speed and has a larger circumference, thus moves more with each turn.

So, sidewall flexing caused by higher profile is not all that there is to a tire, specially with tires as wide as they have in F1, where the effect of the wall "lifting" the patch is not as notorious as in regular cars, with narrower tires.
Ciro
Ciro Pabón
 
Joined: 10 May 2005

Post Fri Nov 02, 2007 3:03 am

vis wrote:I think they have to fit small 13" rims to be forced to use little diameter brake rotors, otherwise with 18" or so they could fit larger brake discs....

Regardless of wheel diameter, brake disc sizes are a mandated size, in both diamater and thickness.
limited to 28mm thickness and 278mm diameter by the FIA

Brake Systems
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mx_tifoso
 
Joined: 30 Nov 2006
Location: North America

Post Fri Nov 02, 2007 10:54 am

It's definitely 'the look' too, people recognise the look of the car, the wheels and associate it with F1.
zac510
 
Joined: 24 Jan 2006
Location: London

Post Fri Nov 02, 2007 4:56 pm

If the tyre takes part of displacement caused by the irregularities on the road, you can use a smaller suspension vertical displacement, in the A-arms. In turn, this could mean that you can use a slightly lower body, closer to the ground, so you get higher downforce, but it is just a thought.


But surely, from a ridehight point of view, it doesn't make any difference whether the vertical displacement is from the tyres or the suspension, the only difference being with the suspension you have much more control over the spring rates and damping?
williamssam
 
Joined: 12 Oct 2005
Location: Stamford, England

Post Fri Nov 02, 2007 6:38 pm

williamssam wrote:But surely, from a ridehight point of view, it doesn't make any difference whether the vertical displacement is from the tyres or the suspension, the only difference being with the suspension you have much more control over the spring rates and damping?


That's true, but remember the spring rate for tires is highly adjustable in the form of tire pressures and carcass construction. I know that they don't actually change out spring rates of the suspension during the race and with the tire pressure they can technically do it quite easily if necessary (something that is really important during wet races).
I love to love Senna.
ginsu
 
Joined: 17 Jan 2006

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