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Old 18th February 2008, 08:56   #1
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Tires best operating temp / maximum adhesion?

I know it all depends on what brand and what type of tires are used, what the ambient temperature is, and other factors, but typically, to the best of your knowledge and experience - what is generally the best operating temperature for car tires where it provides the best grip / maximum adhesion?
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Old 18th February 2008, 19:41   #2
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I found the following link with some optimum operating temperatures shown. I'm talking about summer tires obviously, because discussions of winter tires in the context of optimum grip really doesn't apply since they are designed to perform in the opposite extremes.

I know during the summer, my tires are significantly hotter than in the winter. Since the only sources of heat input into the tires are the road surface and friction generated, it stands to reason they will never reach the optimum temperature for grip during the winter months. In fact, even if the ambient temperture is say 60 degF, the road surface could still be at 40 degF if the previous week or two has been cold. This is somewhat supported by the condensation that frequently forms on the road surface when the ambient air just begins to warm up.

Also, I fired off an email to Toyo and they said they did not have a chart that shows grip versus tire temperature. However, I did find a writeup that shows the exact chart I was looking for (see page 21 of the 2nd link). Although the curve could shift left to right or even the slope change versus manufacturer, it still points out that there is an optimum range for tires to operate.


http://www.elephantracing.com/techtopic/tiretemp.htm

http://books.google.com/books?id=cr4...9rL5oc#PPP1,M1
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Old 18th February 2008, 21:32   #3
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Thanks!

Excellent info Mr. bimmernut1!

Thank you!
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Old 18th February 2008, 23:46   #4
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No problem.

The interesting part of the graph to me is how steep the curve is and how fast the grip drops off at temps below approximatly 120 degF. I haven't tried to extrapolate down to to the 50-60 degF range. But just eyeballing the chart seems to show the grip could be as low as 60-70%.

I guess that's not a big surprise but still good to be aware of.
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Old 19th February 2008, 05:36   #5
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Quote:
Originally Posted by bimmernut1 View Post
The interesting part of the graph to me is how steep the curve is and how fast the grip drops off at temps below approximatly 120 degF. I haven't tried to extrapolate down to to the 50-60 degF range. But just eyeballing the chart seems to show the grip could be as low as 60-70%.

I guess that's not a big surprise but still good to be aware of.
With summer tires there is a huge step-function like drop off in grip as you approach the glass transition temperature of the compound (which is essentially a phase change). This typically is near and below ~35F. Hence the reason you never want to run them in snow/ice since traction is essentially zero under those conditions. You also want to be aware of the loss of grip when driving on dry pavement in cold weather too. Don't overestimate the potential traction you think is there. When you look at R-compound tires, temperatures below 35F or so can actually damage the tire's rubber compound. Toyo has a warning out for their R-comp tires about storing and/or attempting to use them when temps are below 35F. Also as a regular summer tire ages after many heat cycles, the sensitivity to loss of grip is more apparent as a function of temperature.

You can easily see this with summer tires on the M5 and trying to launch the car. If the ambient temp is 90F versus 50F, there is a huge difference in the launching rpm to be used and the rate at which you can feed throttle in 1st gear without spinning too much. Drop that temp to 30F, and it is yet again a huge difference from 50F.
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