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Tyre pressure and track temperature


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#1 Flamini

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Posted 25 August 2009 - 09:47

I always wondering what is relation between tyre pressure and track temperature. For instance, track requires middle tyre pressure in standard track temperature. But what if:
1) track temperature will be higher?
2) track temprerature will be lower?

In my opinion it will be somethig like:

1) Higher track temperature can warming tyre faster pressure but also destroys tyre faster
2) Lower track temperature can causing problems with warming (to less warming) but life of the tyre can be longer

So the solution is:

1) set lower tyre pressure
2) set higher tyre pressure

And my question is: how big are the changes? Imagine we have 3 tracks:
1) requires low tyre pressure
2) requires middle tyre pressure
3) requires high tyre pressure

Could it be possible that changes are so big that with much lower (than standard) track temperature on track 1 they have to use values of tyre pressure which suit on track 3? Or track temperature on track 3 is so high that they have to cut down values of tyre pressure to values which suit track 1?


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#2 scheivlak

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Posted 25 August 2009 - 09:56

Good questions Flamini and welcome - you'll get the best answers probably from the Technical Forum here: http://forums.autosp...php?showforum=8

#3 Flamini

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Posted 25 August 2009 - 10:17

Good questions Flamini and welcome - you'll get the best answers probably from the Technical Forum here: http://forums.autosp...php?showforum=8


Ok, thanks for answer and sorry for bad place :)

#4 Joe Bosworth

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Posted 25 August 2009 - 11:43

Flam

I think that most people will end up telling you that the colder the track the higher the starting pressure that you will use.

The reason for this is that you want the tire to come up to a given temperature for best shape and road/rubber interaction.

Lower track temperatures provide two fqctors. The first is that you will not pick up as much heat so temperature build up will be lower so you need to start from a higher base to get to the temp you want. The second is that a higher starting temp gives you a smaller foot print so that temp will build faster.

There is a small dichotomy in this and that is that at some point the lower temps provide for more side wall work that builds temperature but in my experience this is a small factor.

All in all the range in high to low starting points is less than 2 psi.

It will be interesting what advice others provide!

Regards

#5 meb58

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Posted 25 August 2009 - 12:36

I will add that tire type works into this as well. A Toyo RA1 compared with any Hoosier...regarding the Hoosier, tread temps do not reach the core and can cause delamination if track temps are too low....below 60 deg F +/- I think. And although the RA1 cannot compete with a Hoosier when track temps are warm enough, the RA1 will span a larger track temp range with fairly good results.

Unfortunately, I assumed that less psi would allow the sidewall to deform a bit more adding to heat but I see the thinking...and I somewaht cringe thinking about driving a few laps...what is happening to those sidewalls as tire temps come up?

...could also use nitrogen...

#6 Paolo

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Posted 07 July 2010 - 08:11

About tyre temperatures, just found interesting info on this week's Autosprint: Pirelli states that F1 tyre temperatures typically top around 105 celsius, compared to 130-135 in other categories such as Rally, Gt.

This calls for softer compounds to be used in F1.

#7 johnny yuma

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Posted 07 July 2010 - 09:02


The track on a cool cloudy day probably same temperature as your tyres before you go out,so the heat you gain will all come from friction when you start cornering,not the
bitumen.So start with brand-recommended pressure cold,which can vary, but 3 to 4 below desired hot temperature is common,and remember tyre is in contact with road on
small % of circumference ,and is cooled by air at other times........go easy for a lap or two ,probably not a big issue.

On a hot sunny day if the track temperature is extreme,and your wheels have been in a cool pit area,you might start 1 or 2 degrees further below recommended cold,but
certainly no more ,as stated by Joe Bosworth.


PAOLO--Can that 130-135 Celsius be right ! Maybe for moments ,but measured in the pits ??? Way beyond boiling water ??

#8 Paolo

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Posted 07 July 2010 - 09:19

PAOLO--Can that 130-135 Celsius be right ! Maybe for moments ,but measured in the pits ??? Way beyond boiling water ??


Pirelli speaks of "peak" temperature, so it is probably meant while running.


#9 adam1312

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Posted 14 October 2012 - 19:29

lower temp- lower pressure

#10 Lee Nicolle

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Posted 21 October 2012 - 23:27

The track on a cool cloudy day probably same temperature as your tyres before you go out,so the heat you gain will all come from friction when you start cornering,not the
bitumen.So start with brand-recommended pressure cold,which can vary, but 3 to 4 below desired hot temperature is common,and remember tyre is in contact with road on
small % of circumference ,and is cooled by air at other times........go easy for a lap or two ,probably not a big issue.

On a hot sunny day if the track temperature is extreme,and your wheels have been in a cool pit area,you might start 1 or 2 degrees further below recommended cold,but
certainly no more ,as stated by Joe Bosworth.


PAOLO--Can that 130-135 Celsius be right ! Maybe for moments ,but measured in the pits ??? Way beyond boiling water ??

I think that may be farenheight

#11 Lee Nicolle

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Posted 21 October 2012 - 23:36

Watching Bathurst a couple of weeks ago with the Stupicars all destroying tyres. They were starting around 18psi!! And chasing about 32 34 psi.This with a steel belted tyre.
I have always started between 4 and 6 lbs down on the fronts and 4-8lbs down on the rears. This on Kevlar belted slicks, old crossply slicks and these days on steel belted semislicks.
From there it is trial and error.
Someone mentioned Toyo v Hoosier. The Hoosier to me is a starnge animal. My one effort with them I did not like though I may try them again in softer compound. Unfortunatly the info given by them for correct 'curing' of the tyre is useless for a hillclimb. The sofetr ones do seem to hang in there, at least for Supersprints and short races and seem to keep coming back. Though the curing instructions can be followed at that type of event.