F1 tyre profile

[West]

the higher wall allows the tyre to adsorb larger bumps, like kerbs or the occasional marshall you can run over.

I'm getting tires soon; I'll take the latter in mind when I have a "work sucks" day (which is everyday)

[persovik]

The only reason F1 tyres have got the high profile is because of regulations. There are avantages of high profile, such as traction etc., but the performance of an F1 car is compromized by anything that prevent it from having a stable ground clearance. Since the rim size is set, the profile is given by the other dimensions, e.g. the max diametre of the tyre. Reducing tyre diametre would compromize performance by necessitating harder rubber, so that isn't an option either. In order to contol the tyre in any vehicle, you want the suspension travel should far exceed movement in the tire, otherwise you have a hard time efficiently damping the tire. (unless of course you have efficient mass dampers, that have been outlawed).
Originally, the rim size was reduced to force smaller brakes, but the brakes have since been regulated by their own rules, so at the moment the rim size regulation is there to prevent the development of ulta low profile tyres that would allow for more efficiency in the undertray, leading to more speed, and also higher risk due to a higher sensitivity.

[Ciro Pabón]

I differ.

Now, I googled around. Then I come back to repeat what I read:

- F1 cars work at the limit for a long time. Low profile tires offer good grip, but the fading of the tire is sudden. High profile tires are more driveable allowing for a "gradual loss of grip".

- Low profile tires have a "hard time getting rid of heat". High profile tires offer a larger surface

- High profile tires allow for "more pressure build up without failure"

- Low profile tires are closer to the rim and heat rapidly because of thermal transfer from the brakes through the rim.

- "... on road cars or GT cars, the suspension is much much softer than that of an F1 car, and because of that, the low profile tyres work effectively because the suspension is absorbing much of the bumps and undulations on the surface, but in a formula one car, the suspensions are harder and aerodynamics are much more of a consideration and grip source. Because of that, there is much more loading and demand on the tyres, and the higher profile does multiple things in that regard."

I also read that the Lotus 72D had low profile tires, BUT then skirts came along, spring rates increased and for some years "karts at 200 mph" were built, with spring rates as high as 3000 pounds/inch. End of low profiles.



This meant that high profile tires came back to save the backs of the drivers.

So, maybe the answer is not as simple as persovik explains. Is that, or I googled only the wrong sites...

[mx_tifoso]

Ciro, would you mind sharing with us the sources you used for the previous post? Se lo agradezco desde ahorita.

[Ciro Pabón]

Sure.

• - F1 Nutter: The aerodynamic evolution of F1 cars http://www.f1nutter.co.uk/tech/aero.php
  
  - Low profile tires: Linksheaven F1 Forum http://www.linksheaven.com/forums/index ... topic=4500
  
  - "... If I had my way we would have low profile tires with tread as we have on modern road cars, which would look better and look more modern."
  -- Max Mosley -- http://atlasf1.autosport.com/2000/can/p ... keefe.html
  
  - "... lower profile tyres would be introduced in order to give the wheels and tyres a more modern look and also permit more freedom on brakes and suspension"
  -- PROPOSED CHANGES TO THE RULES FOR THE 2008 FIA FORMULA ONE WORLD CHAMPIONSHIP -- (June-2005) http://www.fia.com/mediacentre/Press_Re ... 05-02.html
  
  - A history of Shadow http://www.vintagerpm.com/shadow_history.htm (CanAm low profile tires, discarded).
  
  - Mercedes low profile tires susceptible to impact and low pressure http://en.allexperts.com/q/Tires-2359/l ... ubbles.htm
  
  - SUV low profile tires susceptible to off-road impacts http://en.allexperts.com/q/Tires-2359/L ... ires-3.htm

I stop there, is taking more time to write about the references than reading them...

To be fair, persovik mentioned the sensitivity, which is one of the arguably good/bad characteristics, or if I understand him, low profile tires are more sensitive to steering but are more unforgiving when you slide.

Besides, I don't know how low can the low profile be before the tire hits the rim while riding the kerbs. So, probably persovik is right, and a change in regulations would bring lower tires, even if not as much as the "ricer" ones, because of the other influences I mention.

Finally, if you used solid rubber tires (there is no lower profile than that) the effects would be taken to the extreme, for discussion purposes. You'll get a very low energy absorption in bumps and lack of thermal stability: you brake, the tire melts.

Low profile tires would have another "very important advantage" that persovik, inexplicably, forgot to mention: the drivers, when entering the car, would be forced to "bend over" a little more "toward" the team owners... perhaps Alonso could use them next time he drives for McLaren.

[Carlos]

The Shadow CANAM car used truly wonderful and weird tires a brilliant experiment as so many CANAM cars were. As you can see from the cars stance and the width of the front fender bodywork... this is from menory but the tires were on little tiny rims..12 or 13 inches daimeter and about 20 inches wide...thats 30cm by 50cm, the idea was a very low CG and minimal frontal area, with these strange tiny A arm suspension with little . little progressive wound springs that looked like springs out of a Rolex watch; anyway those tires that were almost as wide as the Golden Gate Bridge required so much driver effort, George Folmer complained about it, so did others ... that it was hardly drivable, just a totally exhausting afternoon... the next car was more conventional tire wise... how they persuaded Goodyear to do those custom tires I will never know...but the great thing about the CANAM was the spirit of innovation...somewhat lacking today?

On a serious note low profile tires have a faster 'turn in' to a corner, a crisper feel, this is my past experience with road cars from a few years ago... less sidewall flex is the reason...but F1 rules are rules.

[IMG:600:375]http://img213.imageshack.us/img213/531/ ... sesrq2.jpg[/img]
This picture shows just how tremendously wide those tires were.

OT...Just heard on NPR radio why oil is at $95.... a real surprise... it turns out that the steel 55 gallon barrel costs $90USD to make and the oil to fill it costs only $5USD...I think thats what they said

[persovik]

I differ.

Yes, higher profiles offer a lot of advantages, they give better traction, they are more forgiving, easier to drive, less prone to damage etc. etc.

However, in terms of absolute performance in a car relying so much on the undertray, they are ultimately inferior.

Very often I hear the explanation that the cars need the high profile because the suspension is so stiff, as if the suspension was a fixed parameter that needed to be adjusted by the design of the tires.
It is like saying that it is cold in the Arctic because of all the ice, or because the polar bears have got thick fur.

I am not a fan of ultra low profile tires, the have got narrow tracking angles, thus giving little warning to the driver, they have got no "wind up" in acceleration, thus providing less manageable traction off corners, they easily get damaged on curbs, they are sensitive to wrong tire pressure,..... I could go on forever.
One thing in favour of ultra low profiles; you have got a much better response to changes in suspension set-up. If that is a good thing, when you get it wrong it's horrible, like many of us have experienced when swapping our perfectly working standard tires on our road cars for something that really requires a retuned suspension.

Would the cars be quicker if the suddenly were fitted with 18" rims? No, not for a while, they would be slower, crashing more often and leave a lot of frustrated drivers stranded in gravel traps or worse. They would probably struggle to get the power down off the corners, particularly without TC.
What would happen though, in the longer perspective, is more sensitive aerodynamics, with undertrays producing more downforce in a narrower window of operation.

[Carlos]

I obviously got some details wrong about the Shadow's LOW PROFILE TIRES

Pete Lyons, the absolute dean of CanAm covering race reporters, continued: The car is hard to believe even when seen, so tiny is it, literally knee-high. It all depends on the minute Firestone tires, which have 11ins and 16ins footprints but are mounted on wheels 10ins and 12ins in diameter."

Probably the lowest profile car, with the lowest profile tires ever made?

[IMG:400:227]http://img208.imageshack.us/img208/6177 ... ingvy9.jpg[/img]
The Original Shadow CANAM Conception

[Belatti]

Carlos, are these the guys that drove that CanAm car?

[modbaraban]

Or these...