20" Hoosiers for the GT3

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05-25-2017, 04:08 PM

#31

GrantG

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Thanks for the update (991.2 GT3 and 911R use these first available sizes too).

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05-25-2017, 05:03 PM

#32

tqevo

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I wonder how close to Hoosiers the new Cup 2 N1s are... I bet R7's would be worth at least 5-7s on the ring.

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05-25-2017, 05:07 PM

#33

James-GMG

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Perfect timing as this will certainly make the already capable GT3 even more fun to drive!!

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05-26-2017, 06:29 PM

#34

IRguy

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Quote:

Originally Posted by Mass_K

Sure... the volume is not totally constant, but it will not keep increasing as the pressure increases. It gets to a point where the tire won't flex anymore, which is theoretically (at that point) a constant volume. Thus with the increase in pressure the temperature of the air will increase within the tire. Due to temperature equilibrium, the air will transfer its heat energy into the tire, ultimately increasing the temperature of the tire.

If I'm wrong I'm wrong, but that is my opinion on the matter. I guess you could take into consideration the fact that the rubber will flex less creating less heat in the tire, but from a technical point of view, i.e gas laws, the temperature of the tire will be greater with increased pressure.

You would be correct based upon the PV=nrT - increasing pressure means increasing temperature at constant volume of constant quantity of gas (nr) However the nr is not constant since you are introducing new gas to a chamber (tire). That is causing the increased pressure.
PV=nrT describes the relationship among temperature / pressure and volume of a given quantity of ideal gas. But in our example we are changing the quantity by pumping gas into the tire.
Your assessments is correct on the volumetric change of a tire being inflated is relatively minimal, 2-5% of the nominal volume from nominal pressure to max pressure.
Most heat during driving is generated by tire wall deformation and radiation coming from the brakes.