V8Supercar Setups

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NeilPearson
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Re: V8Supercar Setups

Post by NeilPearson »

thats got to do with over inflation in race trim Exar.

If you have them to high in race trim, they over inflate, and your running on the middle of the tread rather than the whole tyre, and makes the car handle awful.

as i said, in oval racing i dont care about the heat, all i do is get the temperature spread even, so the whole tyre is getting used.
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DarrenM
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Re: V8Supercar Setups

Post by DarrenM »

Scottie wrote:but then why don't flat tyres explode? Mika Hakkinen could have used some over-pressurised rear tyres at hockenheim in 2000!
How do we jump to the extreme of tyres exploding? I'd only expect to see maybe 5-10 degrees difference between low and high drivable pressures, not spontaneous combustion :)

The lower the pressure the greater the angle between the unloaded portion of the tyre and the flattened section of the contact patch as well as increased size of the deformed area and extra side wall deformation. That extra work happening on the tyre will produce more heat.

If the higher pressure causes you to slide more in the corners then you could generate more heat that way depending on compound, surface, tyre construction etc, so as always it's not black and white.

I don't see that video being related to this. The audio said a similar failure for DC was due to the tyre being cut. It doesn't say it failed due to overheating. I assume this is it, because your link isn't working.
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From a couple books I have here:

"Tire pressure and temperature are interrelated--lower initial pressure results in more rubber distortion and higher temperature, which in turn results in higher "hot" pressure"
Race Car Vehicle Dynamics - William & Douglas Milliken

Higher hot pressure depending on the gas used to inflate the tyre of course.

"Any process that involves friction produces heat. Additionally, a portion of the energy involved in compressing and distorting the tread at the contact patch is not restored to the tire when the tread straightens out at the trailing edge but is converted into heat. Some of the heat so produced is radiated into the airstream but some of it is stored in the tire.
...
So two things are important in the tire temperature picture--first to be sure that your tires are operating at a temperature of at least 175 degrees Fahrenheit and, second, to be very sure that you do not exceed the compound limit. You will only exceed the compound limit if you:
(1) run too much negative camber and burn the inside edge of the tire.
(2) run too low an inflation pressure or run with a slow leak.
(3) run too soft a compound for the track or run rain tires on a dry track--which amounts to the same thing."
Tune to Win - Carroll Smith
DUcK
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Re: V8Supercar Setups

Post by DUcK »

Exar Kun wrote:It's definitely higher pressured tyres heat up faster. But there are of course heaps of factors to consider. The heat soak from brakes is a big one and indeed, how much the tyre moves around too. But from years of watching, it's always been about having higher pressure tyres for a qualifying run so they get heat into them faster.
as neil said it's more the fact that they want optimal tyre pressure immediately rather than heat. I would like to learn more about this topic actually, so I will post my ideas on how things work then hopefully someone can tell me I'm stupid and correct me :) but as far as I know the friction is what heats up the inside of the tyre, which is what i assume would increase the pressure, because hot air expands (i think.. lol), which would be achieved by braking heavily then accelerating and braking heavily again and deforming the tyre. the surface temperature is either heated by the inside of the tyre, or it is scrubbed, and it has broken the point of friction/grip and skids along the road therefore only heating the top of the tyre (surface) because by skidding the tyre you aren't deforming it as much as heavy weight loading would do... and i guess the surface temp would seep into the air inside the tyre therefore increasing its pressure.

so because the friction causes more heat inside the tyre, a lower pressure would probably get more 'heat' into the tyre, because the tyre deforms more. but it will take a while for the tyre to reach its optimum working pressure... but i am still not sold that a higher pressure keeps the tyre cooler, because as i think darren stated it forces you to slide around a lot more. which i would assume make the tyre's surface hot, and probably overheat which gives you an over pressured tyre (round, ball shape instead of a large contact patch on the road).

where do i fail? *puts on flame proof suit*
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