Tire to rim ratio

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tk421
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Joined: 12 Jan 2009, 21:34

Tire to rim ratio

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just curious about different racing series' tires and rims. sports cars tend to have larger rims with low-profile tires, but f1 has small rims with very high-profile tires. simple question i suppose, who's got my answer? thanks!

btw im not looking for "because the regs say so"
Best regards. I guess this explains why I'm not at my post!

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Ciro Pabón
106
Joined: 11 May 2005, 00:31

Re: tire to rim ratio

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I looked for a previous answer but could not find it. Can somebody help to locate it?

I remember that the consensus was that in F1, IRL and other series, downforce is high, so the best solution is use the tyre as part of the suspension.
Ciro

timbo
timbo
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Joined: 22 Oct 2007, 10:14

Re: tire to rim ratio

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I thought it is much simpler. Rims are limited to 13" so to get bigger contact patch and torque (from rear wheels) you have no choice but use high-profile tyres.
Maybe too simple to be true?

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

Re: tire to rim ratio

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Reason why F1 runs 13" wheels is that they want to LIMIT the braking capacity of the cars. There are a variety of reasons for the actual tire size.

Sports cars on the other hand run large wheels for huge brakes and lots of suspension packaging room.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

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tk421
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Joined: 12 Jan 2009, 21:34

Re: tire to rim ratio

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Jersey Tom wrote:Reason why F1 runs 13" wheels is that they want to LIMIT the braking capacity of the cars. There are a variety of reasons for the actual tire size.Sports cars on the other hand run large wheels for huge brakes and lots of suspension packaging room.
good points--i hadnt thought of that, but why not have 18" rims and just keep the same small brake size? just because the rims are big doesnt mean the brakes have to be. not knockin ya, just askin! :D
Ciro Pabón wrote: so the best solution is use the tyre as part of the suspension.
i was thinking something along those lines, where they want a large volume of gas inside the tire for some reason. aside from why f1 does it that way, what are the tradeoffs between a very high and very low profile tire in general?
Best regards. I guess this explains why I'm not at my post!

gridwalker
gridwalker
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Joined: 27 Mar 2009, 12:22
Location: Sheffield, UK

Re: tire to rim ratio

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High profile tyres are more sensitive to tyre pressures and thus tyre temperatures, due to the greater volume of gas contained within them being subject to thermal expansion.
"Change is inevitable, except from a vending machine ..."

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ISLAMATRON
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Joined: 01 Oct 2008, 18:29

Re: tire to rim ratio

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more suspension travel within the tire sidewall flex so the suspension does not have to move as much.

timbo
timbo
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Joined: 22 Oct 2007, 10:14

Re: tire to rim ratio

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ISLAMATRON wrote:more suspension travel within the tire sidewall flex so the suspension does not have to move as much.
I'd though it is a negative factor, no? Because tyre flexes almost as a spring without much damping - that's why they used mass dampers IMHO, to offset tyre vibration.

mike
mike
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Joined: 10 Jan 2006, 13:55
Location: Australia, Melbourne

Re: tire to rim ratio

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smaller rims are simply lighter??

timbo
timbo
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Joined: 22 Oct 2007, 10:14

Re: tire to rim ratio

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mike wrote:smaller rims are simply lighter??
don't think rim + tire combo will be lighter with smaller rims. Magnesium rims are damn light while higher tire needs thicker walls etc...

RJC_pt
RJC_pt
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Joined: 18 May 2007, 21:59
Location: Braga, Portugal

Re: tire to rim ratio

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There must be a reason, lmp have difrente size front/rears, bigger front rims, bigger walls rear

Conceptual
Conceptual
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Joined: 15 Nov 2007, 03:33

Re: tire to rim ratio

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Tomba should contact the Bridgestone PR department, and ask for one of them to join this board, and answer all of these questions with the actual reasons.

Wasn't there a Michelin guy that used to frequent here before? I thought I read some old posts by him before...

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ISLAMATRON
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Joined: 01 Oct 2008, 18:29

Re: tire to rim ratio

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timbo wrote:
ISLAMATRON wrote:more suspension travel within the tire sidewall flex so the suspension does not have to move as much.
I'd though it is a negative factor, no? Because tyre flexes almost as a spring without much damping - that's why they used mass dampers IMHO, to offset tyre vibration.
yes and porpoising, but having more suspension travel would make them increase the ride height so they rather go with the big sidewalls.... I think

mike
mike
2
Joined: 10 Jan 2006, 13:55
Location: Australia, Melbourne

Re: tire to rim ratio

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tire flex could give more grip?
since it deforms easier the contact patch changes more readily??
i got an idea of it when they 1st introduce the hard and the soft compound (2007) they say that the soft makes the car move more, but it is still faster.

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

Re: tire to rim ratio

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Conceptual wrote:Tomba should contact the Bridgestone PR department, and ask for one of them to join this board, and answer all of these questions with the actual reasons.

Wasn't there a Michelin guy that used to frequent here before? I thought I read some old posts by him before...
There are at least two race tire engineers about...
Grip is a four letter word. All opinions are my own and not those of current or previous employers.