Quote:
Originally Posted by GTR
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..........
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Theeee most important factor in tire wear is the amount of turns the tire has to make - and how severe the cornering is.
In order to generate the side force necessary to get the vehicle to change direction, the tire has to generate a slip angle. This causes the tire to slide relative to the road surface, which grinds off rubber - and the higher the cornering force, the greater the slip angle, and the faster the wear.
By contrast, driving straight ahead is practically free. Most folks don't have much of a choice about the routes they take and where they drive, but the do have a choice about of cornering severity, so in most respects, this can't be controlled by the driver.
Similarly, a tire's alignment can also generate a slip angle - that is, toe. Camber doesn't play much of a role in tire wear except for uneven wear - and the affect camber has is multiplied by how far off the toe is.
Road surface also is a major factor. Some locales have pretty abrasive surfaces - southern Florida for example. Again, most folks don't have much of a choice here.
Yes, stressing the tires with "jackrabbit starts" and severe braking will cause tires to wear more rapidly.
(Notice I am NOT discussing the tires themselves.)
The above is pretty much in order as I see it. Operating temperature is probably next - with the same thought: Most folks don't have much control of the ambient conditions. To put this in context, it takes a while for a tire to get up to operating temperature - and it takes a while for a tire to cool down - due to the insulating properties of rubber. And the affect of temperature is probably 10% of the affect of cornering. So I just don't see this area being worth the trouble of trying to control. I think we are talking about only a couple thousand miles difference in the life of a 60K tire.
Quote:
Originally Posted by GTR
.......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.
[[There was a quote in here that made some claims about the amount of improvement in performance using the gas mixture - and GTR comments below about that.]]
That is a ridiculous improvement. They were using the wheel as a heat dissipating radiator to increase tire life......
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I'm struggling trying to understand the magnitude of performance improvement. I have no doubt that an F1 team would have enough resources to find very unusual sources of improvements - and that would include the tire inflation medium. And I have no doubt that they could utilize those improvements.
But where I am struggling is that it can make that much difference. If taking the heat away is such an advantage, then the heating up portion of the heat cycle would be negatively affected and it would take longer for the tire to reach a good operating temperature.
Also, I just can't see that taking heat away could extend the life of the tire that much. The tire has to get up to an operating temperature - which means the heat being generated by the tire is greater than the amount being taken away. The temperature will continue to rise after it reaches operating temperature, but it slows as it gets closer to the equilibrium temperature (the mathematical term is "asymptotic".)
I wonder if they were including the amount of time a pitstop for tires was taking - and that is why the numbers were so high. Turning a race from a 3 stop to a 2 stop is an enormous advantage.
Quote:
Originally Posted by GTR
.......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.
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I suppose that "specifically formulated" could cover ordinary materials mixed in a special way - especially if there doesn't seem to be any particular application other than that. I wouldn't be too harsh on the author even if he is exaggerating in order to make a point.