Winter Tires - Pressures Are Down, But Durometers Are Up

[Lunentucker]

So this ridiculous thing has been stuck in my head for a few weeks now, so I thought I'd explore a bit more.
Yes, in colder weather, the tire pressures drop as the molecules in the air get closer together...
BUT, the molecules in the tires themselves also compact with cold, making the tires stiffer and harder (don't go there).
So the question is, do they offset each other equally, or should we continue to run summer pressures in hard cold tires in winter, making the ride less comfortable and possibly not exposing them to optimal even wear?

A quick web search didn't yield much.
Yes, you can find published durometers for various tires, but they're typically at room temperature.
I'd love to see a chart that plots durometers over temperatures from 120 degrees F to say 10 degrees.
Is reduced pressure in winter actually OK, because the sidewalls are stiff and the tread is more firm?

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[chorky]

Man now that is a good question. I suspect the answer would vary significantly depending on what tire you are talking about. Even among 3peak tires, compounds seem to vary quite a lot, and they continue to vary even more as tread wear causes additional effects...

I know for me, whatever pressure I run in summer, I let self deflate in winter. For example, if I am doing all highway driving the front is set to 40, rear 45. But in winter, it lowers to 35'ish front, 40'ish rear. Off highway is a totally different discussion. So as long as I don't air down in the winter for a trip, I just let the temperature adjust pressure as the molecules see fit. So far it has netted a good result between tire wear, traction, and comfort. So when it drops to -20, I do not go inflating the tires more - I just let the pressure drop along with the temperature - so long as it doesn't drop too low of course. Thus far the lowest pressure I can remember seeing was 32 or 33.

 

[Mr.Wilson]

Man now that is a good question. I suspect the answer would vary significantly depending on what tire you are talking about. Even among 3peak tires, compounds seem to vary quite a lot, and they continue to vary even more as tread wear causes additional effects...

I know for me, whatever pressure I run in summer, I let self deflate in winter. For example, if I am doing all highway driving the front is set to 40, rear 45. But in winter, it lowers to 35'ish front, 40'ish rear. Off highway is a totally different discussion. So as long as I don't air down in the winter for a trip, I just let the temperature adjust pressure as the molecules see fit. So far it has netted a good result between tire wear, traction, and comfort. So when it drops to -20, I do not go inflating the tires more - I just let the pressure drop along with the temperature - so long as it doesn't drop too low of course. Thus far the lowest pressure I can remember seeing was 32 or 33.

Why on earth are you running 40 pounds in your tires?

 

[chorky]

Why on earth are you running 40 pounds in your tires?

Weight. And it's only 3 psi higher than the factory setting. When I am on pavement, 97% of it is interstate speeds at 80. So it also reduces drag and improves fuel economy

 

[Volt0]

@Lunentucker that’s an interesting question, and I would love to hear a short answer from someone that’s scientific about it. With that said, my guess is that a winter rated tire with a C load rating is still going to be fairly subtle at 32° F, even down to -10°F. If you’re focused on air pressure inside the tire, well that’s relative to the atmospheric pressure outside the tire. So, unless you plan to drive on the moon, here on earth and away from the poles, I couldn’t imagine much of a difference. You could always live on the edge by dropping 1 or 2 psi. ;-)

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