Tyre behavior information?

[mariano.torre.gomez]

where I can get information on the physics of a racing Tyre in depth, please?
how track temperature and pressure relates ?
and so on
thanks

[munks]

A pretty good and comprehensive source online is "The Pneumatic Tire":

http://www.nhtsa.gov/staticfiles/saferc ... 10-561.pdf

[mariano.torre.gomez]

thanks mate

[mariano.torre.gomez]

any other paper on temperature and pressure?
thanks

[Jersey Tom]

You could spend years working in tire / vehicle dynamics and only come up with a rudimentary understanding of SOME of the effects inflation and temperature have.

Can you be more specific? What exactly are you interested in finding out? What's the end use, or objective here?

[mariano.torre.gomez]

we would like to understand better how to choose the right pressure from a given track temperature in our FR car
how much increases pressure and temperature by lap?
how much times per lap will drop after reach optimum temperatures ?
we are racing in Brasil were normally is hot today track temperature was 56 cent. but suddenly in less than 1 hour dropped to 38 for example and was qualy time.
thanks

[silente]

A simple relationship between tyre pressure and temperatures can be obtained using perfect gas equation. Of course, this correlation is correct for the air inside the tire, not necessarily for the carcass for example. But it's a good starting point, above all when you deal with long runs.

As JT said, this matter is not so easy to deal with, so it'w quite hard to understand exactly how to predict everything, but you can at least build up easy way to find a ballpark.

[ubrben]

we would like to understand better how to choose the right pressure from a given track temperature in our FR car
how much increases pressure and temperature by lap?
how much times per lap will drop after reach optimum temperatures ?
we are racing in Brasil were normally is hot today track temperature was 56 cent. but suddenly in less than 1 hour dropped to 38 for example and was qualy time.
thanks

This type of post is a good example of the myth that you can calculate everything. In theory you could simulate this, but it would be cheaper and quicker to do it at the race track. Heresy I know, but there it is

What this means in practice is that you need to run long enough runs in the first session to get a decent pressure vs. lap plot. Once this plateaus you can know you cold pressure (and set temperature) and you hot pressure. Your needle probe temps give you an approximate hot tyre air temp.

If you reset cold pressures at a different ambient temp then this is a pretty easy calculation if you can assume that the operating temp will be similar. This last point is generally where experience kicks in and even at the highest levels experience usually trumps theory.

To use your example though; say you set your cold pressures at an ambient of 20C and you ran then on the 56 degree track at your desired hot pressure. If the track's now 38C a good place to start would be to assume the running temp will drop is some proportion 38/56 multiplied by a constant.

If you adjust your cold pressure based on this ratio you'll soon see if your constants right - you can then adjust. Do this enough and you'll get a decent feel for what to do.

Ben

[hardingfv32]

"we would like to understand better how to choose the right pressure from a given track temperature in our FR car
how much increases pressure and temperature by lap?
how much times per lap will drop after reach optimum temperatures ?"

I think knowing the answers to these question will not help you to make the car perform better.

Tire performance varies with temperature and there is very little you can do about that under the circumstances that you describe. I believe the tire pressure gage in going to correct for the temperature's effect on pressures, so it is that simple.

Now you could develop suspension settings to change the operation temps of the tires, but that is going to take a lot of testing. There is all so the perplexing subject how varying the tire pressure effects tire temps and tire performance.

Brian

[mariano.torre.gomez]

I was looking for concepts more than formulas
but looks very difficult to get explanations
thanks

[hardingfv32]

If you had a good explanation, how do you think it would help you in this situation?

Brian

[ubrben]

I was looking for concepts more than formulas
but looks very difficult to get explanations
thanks

I'm not sure what more you want? This is so specific to the tyre, chassis, dampers, track surface, driver, etc that there are simply no general rules.

Can you be more specific? Ask one simple question, I'll try and answer and we can build from there.

Ben

[mariano.torre.gomez]

we would like to understand better how to choose the right pressure from a given track temperature in our FR car
how much increases pressure and temperature by lap?
how much times per lap will drop after reach optimum temperatures ?
we are racing in Brasil were normally is hot today track temperature was 56 cent. but suddenly in less than 1 hour dropped to 38 for example and was qualy time.
thanks

basically this my starting point/question
thanks

[Jersey Tom]

Well, come up with a test plan.. go to the track, and do some testing. The answer to your question is going to vary dramatically based on a lot of things. Have to generate SOME data to go off of.

[mariano.torre.gomez]

just arriving from the track
not much time to analysis just debriefing




track Pato Branco anti clokwise
day track@46track@49track@42
20/11/2011 amb@25 amb@29 amb@27
diff vs media
lap session 1session 2session 3 s1 s2 s3
1 42.213 41.995 41.521 0.286 0.318 0.011
2 41.941 42.022 41.472 0.014 0.345 -0.038
3 41.938 41.74 41.411 0.011 0.063 -0.099
4 41.901 41.563 41.531 -0.026 -0.114 0.021
5 41.785 41.371 41.538 -0.142 -0.306 0.028
6 41.745 41.585 41.471 -0.182 -0.092 -0.039
7 41.963 41.75 41.501 0.036 0.073 -0.009
8 41.621 41.502 -0.056 -0.008
9 41.56 41.645 -0.117 0.135
10 41.561 -0.116

overste++ overstee+ exaust
293.486 416.768 373.592
media 41.927 41.677 41.510



tyres 81/82 75/80 82/83 font L/R
temp 88/91 81/88 85/84 Rear L/R

pressure before 14/14 11.5/12.5 11.0/12.0
14/14 13.0/12.0 13.0/12.0

pressure afte 17/17 12.0/12.0 11.0/12.0
15.5/16.5 14.0/14.0 13.0/12.0