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Between reading the "how hot is too hot to ride" thread and having a really boring job, I got to thinkin:D
How big of a difference in terms of traction is there from riding mid-day on a 30 C day compared to say early morning or at night, i.e cooler? I can only assume you'd have your best grip on the hot days, but does it make a huge difference? I realize the pavement surface would be cooler, but do your tires run a lot colder as well giving you less grip?

Ya, like I said...really boring job:p
 

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From an engineering perspective, I have to think the tires are made to operate at some ideal temp, and that they shed (or retain) heat in a more exponential manner when away from that ideal. Just a guess though, since I know little about rubber's heat coeffiicient and the effects of layering in the processes.

Yeah, hotter would be stickier to a point, but the speed rating for a tire, I believe, is there because of the temps that are attendant at high speeds. The higher temps probably cause the layers to separate from belts and each other, thus unraveling into a nasty situation.

But just some guesses :)
 

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I was under the impression that speed ratings where a reflection of the tire's balance and belt strength. Tire wont get that hot spinning at 150mph in a streight line. Its the cornering loads that flex and heat up the tire.
As for pavement temp. My expirience is that traction is best when temps are in the 80deg range. Too hot, and the tar starts seeping up killing traction. Tires can also get too hot, and they start seeping oil at that point.
 

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you'd be suprised how hot they can get in a straight line....

We recently did a trip up the 95 in maine mostly straight.... We did about 100 mi. before we took a rest stop. We were averaging 80 or so till about 10 mi before the rest stop and then we really started pushing it.... well over 130's. Once we took our break I noticed my friends tire was a bit rough looking.... kinda like sand paper. I went over to touch it and it was HOT to the touch.... really hot. It was a warm day about 85-90 and very sunny. When I was rubbing his tire the rubber was rolling up and falling off. Not a ton of it but kinda like when you have dirty hands and you rub them together hard and fast (your hands guys your hands ) :twofinger and dirt kinda rolls up in them.... know what I mean? Hard to explain.

Anyway his tire was the only one doing it... ours were hot but not visibly wearing any rubber off.....

He had new perelli's (sp?)
 

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Hi mainerdr-

The effect you saw is almost something that I would call "pilling" of the tire. It is for that reason that I would think outside air temperatures in the high-60's to low-70's would make for the best performance since the tire would get plenty warm with road friction, but not so hot as to incur integrity breakdown.

If nothing else, cooler temperatures sure helps the performance of carbureted motors!

~ Blue Jays ~
 

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I agree... new pavement on really days when I am really hard on my tires they get a bit greasy... kinda slipery when accelerating... it seams to happen with softer compound tires on super hot days. I know on super hot days the pavement can get well over 100 degrees.... not to mention the heat created when beating on the tires... I know tires are tested at several temps... but it sure would be hard to find a compound of rubber that works well when cold and hot... since the weather can offer such extremes in either direction.
 
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