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Originally Posted by CapriRacer
First, when we talk about racing tires, it isn't wear that is causing the tire properties to change; it's the heat history and the tread compound is what is changing. To some extent the tire manufacturer can change how quickly such a change can take place - and that has been what Pirelli has been doing in F1.
I would think that the issue with the inflation gas is either about keeping heat in the tires, or getting heat out of the tires. I don't recall there being any issues of brake fade in F1 for quite some time, so I don't think conducting the heat away from the brakes is what this would be about.
Heat does have an effect on a tire's wear rate, but a) the inflation gas is not going to have a major effect, and b) the temperature affect is small compared to other things. It would be better to spend one's time concentrating on alignment and gentle driving, rather than messing with the inflation medium.
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Guess I should have been more specific. I know why tires wear in general, and how they break down under heat, and heat cycles, and all that. What I meant was over the life of a 60K mile tire, what are the major vs minor contributing factors to wear, given an average driving behavior.
I'm sure there is some combination of factors such as alignment, camber, driving surface, psi, # of burnouts, load, and temperature. What I was wondering would reducing the average amount of heat generated when driving would tire increase tire life in any significant manner. Probably pretty hard to test that.
As far as F1, they have both problems you mentioned. Getting heat into AND out of the tires. During the first laps the tires are too cold even with tire warmers, then later the tires are too hot and that heat causes the tires to break down. It was the too much heat part that Ferrari was working on. Here is what their results were, supposedly. I think all this info came from the italian court case vs McLaren, and the court released a PDF with the technical info blacked out, but of course they did it wrong and a non adobe pdf app could unblock the info and voila, it was public.
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What Ferrari found out though , was by using a combination hydrofluorocarbon (HFC) - based mixture specially made for use in racing tires. This mix greatly extends the performance of the tires over a number of laps. For instance in the Ferrari testing after 23 laps , tires filled with air had about 40% of the performance of a new tire , where the HFC mixture had 80% of the performance of a new tire.
The mixture of gases also allowed for a much longer tire life before bursting. Where nitrogen would last for 64 minutes before bursting , the gas mixtures allowed the same tires to last from 94 minutes to 103 minutes.
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That is a ridiculous improvement. They were using the wheel as a heat dissipating radiator to increase tire life.
edit: wanted to add that the author for racecar engineering was wrong about the "specifically formulated for race cars" the gas was just 50% standard r404 refrigerant and 50% CO2.