Wheel diameter

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mifune
mifune
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Joined: 05 Oct 2009, 02:27

Wheel diameter

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Why are F1 wheel diameters limited to 332 mm max while LMP1 and 2 cars are limited to 18” maximum?

Jersey Tom
Jersey Tom
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Joined: 29 May 2006, 20:49
Location: Huntersville, NC

Re: Wheel diameter

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Limits the size of the brake package for one.

Just two different rules. 18" isn't necessarily better than 13"
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Shrek
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Joined: 05 Jun 2009, 02:11
Location: right here

Re: Wheel diameter

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i know nascar also does it
Spencer

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Fil
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Joined: 15 Jan 2007, 14:54
Location: Melbourne, Aus.

Re: Wheel diameter

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i vaguely remember F1 discussing a change of wheel diameter as part of rule changes a number of years ago..

what impact would a larger diameter have on the series in racing terms.

as i understand, the current F1 suspension setup relies on the tyres for most of its longitudinal travel. moving to lets say 18" wheels, would severely hamper this reliance.

stiffer sidewalls would allow less latitudinal flex, again forcing more reliance on a different mechanical setup..

would all this slow the cars due to the need for a higher ride height/softer suspension setup?
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mifune
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Joined: 05 Oct 2009, 02:27

Re: Wheel diameter

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The points that you bring up are good and valid, but don’t set me up well to pose an, “all things being equal” question.

As I read the current regulations:

Formula 1
Wheel Diameter max 13"
Tire Diameter max 26"

LMP1,2
Wheel Diameter max 18"
Tire Diameter max 28.5"


What combination makes for a faster car “all other things being equal” say around a fast track like Spa Franchorchamps?

bazanaius
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Joined: 08 Feb 2008, 17:16

Re: Wheel diameter

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It depends what all the other equal things are.

Jersey Tom
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Location: Huntersville, NC

Re: Wheel diameter

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mifune wrote:The points that you bring up are good and valid, but don’t set me up well to pose an, “all things being equal” question.

As I read the current regulations:

Formula 1
Wheel Diameter max 13"
Tire Diameter max 26"

LMP1,2
Wheel Diameter max 18"
Tire Diameter max 28.5"


What combination makes for a faster car “all other things being equal” say around a fast track like Spa Franchorchamps?
There is absolutely no such thing as "all other things being equal" for this kinda question. I have no way of even attempting to answer it.

They're just different. One is not necessarily better than the other.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

Formula None
Formula None
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Joined: 17 Nov 2010, 05:23

Re: Wheel diameter

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Why did F1 cars in the 70s & 80s use smaller diameter tires at the front? Was this for visibility or other reasons entirely?

Image

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Ciro Pabón
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Joined: 11 May 2005, 00:31

Re: Wheel diameter

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Well, Toshiro, in first place, welcome.

Secondly, I think that choosing different tyre diameters is like choosing between using a Hawaiian shirt and using Tuxedo. Allow me to explain.

You can look horrible or very nice, no matter which one you choose. It's all a matter of how you approach the thing.

However, you don't ask (at least initially!) which one is better (people here answer by reflex!) but why they (that is, FIA) chose that way.

So, we could be interested here in what FIA said then, at the moment of the change.

For that, you need an historian, not a technician... and one with some years on him.

As I'm neither (I only pass the years test), I can only tell you that the arguments given by the people that took the decision are not that easy to find.

I looked for 5 minutes and threw the towel.

Does somebody know why? I mean, does anybody knows what FIA said when they were asked why they were changing diameters? (as opposed to explaining why you think one of them is better).

Huge difference, even if FIA was wrong and you are right.

(yeahhhh, suuuure. On my part, I have a good opinion of myself, I think tyres are my very good friends, I love them, they love me, but I have not such an excellent opinion of myself as to second guess FIA here: tyres are also like sunsets, sigh... they vary in such a subtle way... beyond comprehension and memory).

Of course, I'm hearing right now a song by Héctor Lavoe, called "Siento" ("I feel") that says something like: "las chiquitas son bonitas, son bonitas, bailan bien" ("the smaller ones are pretty, they are pretty, they dance very well").

Shake-ira. 18 inches or 332 mm? Is there a limit to the brake package? Go figure...
Image

It is also true that the taller ones are more... cushioned? Of course, they are harder to handle around the ballroom... erm, I mean, the track. You have to anticipate their movements, they're not that fast to react.

Taller Oluchi could be slower (good!). Brake package has moved to the front but appears equally effective. Visibility? Other reasons? Is she trying to set up mifune? Hard to say.
Image

I think my good friend bazanaius summed it up perfectly: what all the other equal things are?

I would add that opinions are like scantily clad women: they show you almost everything, but they don't show you the essentials. Besides, sometimes they confuse some persons and they can make some people angry.

Why that happens, beats me: engineers always prefer hands on testing and actual measurements of performance.

For example, you could compare performance or time after/before a huge change in diameter and you'll reach your own conclusions . End of discussion. You could use also the same method for tyres, now that I think about it...

After/before: larger rims won't necessarily improve your performance
Image

I better shut up. Metaphors are not taking me far, anyway. The point, I think, is what FIA said.

No offense intended on my part toward the numerous female readers of this forum, btw.
Last edited by Ciro Pabón on 06 May 2011, 08:45, edited 1 time in total.
Ciro

CMSMJ1
CMSMJ1
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Joined: 25 Sep 2007, 10:51
Location: Chesterfield, United Kingdom

Re: Wheel diameter

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Bravo Ciro =D>

Women and F1 tyres..awesome.

I understand from my own reading that there were no regulations for wheel size and that the driving factor was whether you could get tyres for your car and what size the tyres were.

I'll try and find the references and for inspiration, I may look at the Shakira gif again...
IMPERATOR REX ANGLORUM

Formula None
Formula None
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Joined: 17 Nov 2010, 05:23

Re: Wheel diameter

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So what you're saying, Ciro, is the FIA mandated big rears & small fronts? What did they have against a more balance look? Large fronts do reduce top speed, but they look better in motion. I don't know, the other look must have been in vogue those days. They were also pretty hairy to drive back then, as I understand it.

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Ciro Pabón
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Joined: 11 May 2005, 00:31

Re: Wheel diameter

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Well, I think I know what I've written. It's harder to understand what you conclude.

Anyway, read this to see what you think... I apologize to veterans for quoting again this piece of... Tao.

Book 7 - Corporate Wisdom

Thus spake the master engineer:

"You can demonstrate a car for a corporate executive, but you can't make him understand mechanics."

7.1

A novice asked the master: "In the east there is a great tree-structure that men call 'International Federation'. It is bloated out of shape with vice presidents and accountants. It issues a multitude of memos and regulations, each saying 'Go, Hence!' or 'Go, Hither!' and nobody knows what is meant. Every year new names are put onto the branches, but all to no avail. How can such an unnatural entity be?"

The master replied: "You perceive this immense structure and are disturbed that it has no rational purpose. Can you not take amusement from its endless gyrations? Do you not enjoy the untroubled ease of designing beneath its sheltering branches? Why are you bothered by its uselessness?"
Ciro

Richied76
Richied76
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Joined: 18 Aug 2010, 21:04

Re: Wheel diameter

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the reason talk of an 18" tire was involved was because michelin, when tendering for f1 last year, wanted to incorporate the LMP programs and F1 programs together to make it more road relevant

Formula None
Formula None
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Joined: 17 Nov 2010, 05:23

Re: Wheel diameter

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Ciro Pabón wrote:Well, I think I know what I've written. It's harder to understand what you conclude.
Double entendre, mi amigo. Too subtle? It's like when kids movies have jokes for the adults to understand, except more vague and apparently no ones laughing... :/

.........

Regarding FIA rules, maybe it was just a way to reduce speeds? Smaller tires having a shorter lifespan?

Or... Were they still cross ply tires in those days? Smaller sidewall to reduce the the sidewall flex?