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It has been very hot lately, up to 106 and 103 degrees F (41 and 39 degrees C).

I went for a ride and got a puncture flat both times. I don't usually get flats. Is it possible the heat of the road makes the tire rubber softer?

I'm running continental grand prix 4 season. I'm thinking because the cold weather compound its more susceptible to heat?

Or just coincidence?

  • 1
    The only issue I’ve ever had due to hot weather was patches coming off the tube. I think they were ParkTool pre-glued patches. – Michael Sep 16 '17 at 9:18
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    I can only speculate, but it seems possible that the road is softening in the heat, and a sharp bit of gravel or asphalt is getting glued to your tire and eventually puncturing it. – Adam Rice Sep 16 '17 at 15:24
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    @Michael - even in the best of conditions, pre-glued patches don't work reliably. =) – Batman Sep 17 '17 at 5:10
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    In my experience, rain is a bigger factor than temperature. But, generally speaking, a tire chooses the most miserable conditions possible for going flat. – Daniel R Hicks Sep 17 '17 at 12:47
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This is a matter of some debate. The New York Times article "Does Hot Weather Cause More Bike-Tire Problems?" by J. David Goodman (July 22, 2010) may be of interest.

The claims in support for hot weather causing problems are that the tubes may be running higher pressure than designed, or the rubber softening making it more permeable. I, like many others, don't believe these claims hold water (however, I don't have appropriate test rigs or the will to verify this).

The biggest flaw with hot weather causing problems is that tires, tubes and rims are tested at pressures way past whats on the label (and for almost all riders, they should be using pressures way lower than the label). So, you're likely quite far from the limit of failure. 100 F isn't an unreasonable summer temperature for a large number of people (the Southwest, particularly), and it would be ridiculous to engineer a tire that couldn't reliably last at 110 F air temp riding conditions, since that would give a very small margin of reliability.

However, I wouldn't necessarily call it a coincidence. In summer, your mileage increases versus winter, and you're likely to see more road debris (from drivers, liter, etc.). Compounding the increased mileage with tubes and tires that may not be in great condition could see an increase in flats.

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    Could tyres wear faster when they're warmer ? Warmth equates with more grip, which means they may lose surface faster and be a bit thinner than you might realise. – Criggie Sep 16 '17 at 8:50
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    Thank you, very interesting read. What do you think about the temperature of the pavement 140+? I'm sure the tire engineers have thought of this obvious fact... Doesn't natural rubber vulcanize at as low as 150 degrees? lhaps.com/images/DogTemperatureArticle_09jun2010.pdf sciencedirect.com/science/article/pii/0032386177902877 – Byron Whitlock Sep 17 '17 at 4:50
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    I agree that hot weather isn't going to cause significant overpressure but I think your reasoning overall is flawed. The failure limits you're talking about are limits for catastrophic failure: the tube bursting like a balloon. Essentially, you're saying that hot weather isn't going to cause catastrophic failures, so it has no effect. However, it seems plausible that hot weather could weaken the tyres (by increasing pressure and softening the rubber) to a level that isn't close to catastrophic failure but which makes routine failures, such as punctures due to road debris, more likely. – David Richerby Sep 17 '17 at 12:21
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    @ByronWhitlock It's a very good point that pavement temperatures can be much higher than the air temperature. But I'm not sure what you mean by rubber "vulcanizing". Vulcanization is the process by which sulphur is added to natural rubber to increase its strength: it can't happen without additives and it makes rubber stronger (though less flexible), rather than weaker. – David Richerby Sep 17 '17 at 12:25
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    Do note that, while the air temperature may be "only' 100-110F, the temperature of the asphalt road is likely 150F or greater. – Daniel R Hicks Sep 17 '17 at 12:49
3

Combination of multiple things, I think.

  1. Nicer weather so you're out on the bike more. More distance travelled means more chance of a puncture.

  2. Nicer weather means less/no rain. So road debris build up and don't get washed to the gutter as quickly. More chance of a puncture.

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    (2.) seems logical but if you watch cycle racing on TV you'll notice that the riders have more punctures on rainy days! Rain makes tiny flakes of flint from the road surface stick to the tyres. – Carel Sep 17 '17 at 8:03
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    @carel yes moisture increases punctures by making small/sharp things stick to the tyre and get several rotations to embed into the rubber. I guess "average days" have the lowest puncture incidence, not too hot nor too wet. – Criggie Sep 17 '17 at 10:57

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