Why do tires go flat in the winter?

Well you've probably been there. It's the first significantly cold day of the season, and you turn your car on and the tire pressure light comes on. This is an annual problem for many of us, and we probably don't even really think about why it happens. I mean we all know it happens when it's cold, but what's happening at the molecular level to make our tire pressure low when it's cold? Let's find out.

125 Flat Tires

Melissa: Hey, I'm Melissa.

Jam: I'm Jam

Melissa: And I'm a chemist

Jam: And I'm not

Melissa: And welcome to chemistry for your life.

Jam: The podcasts that helps you understand the chemistry of your everyday life.

Melissa: Okay Jam. So we're going to take a quick break from the coffee series. gonna talk about something a little different.

Jam: Okay. Does it taste as good as coffee?

Melissa: It doesn't taste it all. Hopefully.

Jam: Ok, is it interesting?

Melissa: I think so. It's one of my favorite, most often thought about chemistry and everyday life situations, especially in the winter.

Jam: Okay.


Melissa: that's why I picked it.

Also. I wanted to take a break because the chemistry of decaffeinating coffee is the next episode up. And it's a little bit more complex and we had a very quick turnaround between recordings. So I really want to do it, invest the time to make that one good. This one I could prepare much more quickly, so we should be back with decaffeinating coffee in two weeks.

Jam: Okay.


Melissa: Also, even though we're recording this episode closer to the beginning of December, this episode should air on December 23rd. That's very close to the Christmas holiday for those who celebrate it. And a lot of businesses are closed and people will be going home, even if they don't celebrate that. So we really hope that you have safe travels and that this will keep you some company when you're traveling between places or doing whatever you're doing.

Jam: definitely. Definitely.

Melissa: And if you want to send us pictures with your family Or of you listening to the podcast, while you're walking around, wherever, whatever you're doing, we'd love to see it.

Jam: Or if you're wearing your chemist-tree sweatshirt

Melissa: Oh yeah, definitely.

Jam: around your family or friends or whatever in the holidays, we'd like to see that too,

Melissa: I busted that sweatshirt out November 1st, so definitely send pictures. Okay. So today we're going to talk about something cold related because hopefully it's cold for Christmas because the weather has been hot here and I'm annoyed by it. So we're going to talk about something cold that, that gets me in the holiday spirit.

Jam: Okay. Okay.

Melissa: And that is why your tires sometimes go slightly flat in the winter.

Jam: Okay. Interesting. I definitely experienced that.

Melissa: Yeah, where it just is a colder morning and your light pressure comes on. And then actually sometimes when it heats back up, it goes away.

Jam: Yeah. Yeah.

Melissa: Okay. So do you have a guess as to why that happens?

Jam: I do, because I think we've talked about like the different ways, like, you know, molecules behave and stuff like that. When temperatures are high, temperatures are low, obviously what's in our tires is a gas.

Melissa: Uh huh.

Jam: So there's not like that really changes whenever, you know, it's not so cold that it stops being a gas or whatever.

It's like our whatever's in our tires turns to liquid or something.

Melissa: That would be crazy.

Jam: But my basic understanding what it would seem to make sense based on what we've talked about in other episodes is that the molecule of the gas get closer together in some way. And so the pressure we've talked about, like steam pressure and stuff like that when we talked about boiling water, seems like it would be go lower because the temperature is lower.

Melissa: That's exactly right. This is the first time that's ever happened. Did you know that before this, or did you use what we talked about when we talked about water freezing and, um, the sea level rising and that stuff, did you take that and apply it to this situation?

Jam: think it's two things. I think it's, I have the knowledge that we've talked about it from this, from the podcast specifically to explain it in chemistry terms. I also think as a kid, I've always known, it's a rule that this happens when it's cold.

So it's like, it's like, like your tires are gonna go flat when it's cold, so it's not.

It's something I kind of intuitively felt like it makes sense, but I would probably not have had the language to describe why, um, without the podcast.

Melissa: Well, I have, I, we can quit now. I have succeeded. This podcast is over officially. Just kidding. No, I have more stuff to add to it, but that is excellent. Okay. So the thing I imagined, the analogy that came to my mind was children.

Children is the most easy thing For me to think about.

molecules. I think, cause there was like packs of them that, you know, go around together and they behave similarly to molecules where they, once they get energy, they move around a lot more when they're tired, they bring it back in. So I thought of, if it was a group of kids with their families, camping, And during the day when it's nice out and they're getting energy from heat and the light and the food that they've eaten, they have a lot of energy and they're all over the place.

And they're really putting pressure on the parents to keep an eye on them. They're going out into the woods. They're going to look at the Creek, they're doing whatever they're all over this campsite, but as it gets colder and they get sleepy and their energy levels go down, they bring it back in.

Jam: Oh yeah.

Melissa: pressure lifts off the parents a little bit.

Jam: Yes.

Melissa: And so there there's less pressure as a result of their actions. And that is exactly what happens with molecules. Like you described. As we put energy into molecules, the reason things go from solid to liquid, to a gas as they heat up is that they have more energy and movement. As you put more energy in that energy results in more movement and solids, the molecules will slightly start to vibrate or do slight movements.

And then as it breaks apart from one another, then it turns into a liquid where the molecules are moving around even more. And then if you put even more energy in, they will separate out into the gas phase. But if it starts to cool back down, they gas begins to come closer together and they. Molecules have lower energy.

They have less movement sometimes we even get condensation. So for the tires, the air that is in your tires, there's no water. So it should stay in air. As it gets colder at won't turn the liquid or freeze, you'd have to work really hard to do that, but it will do exactly what you said. The molecules will come back together and there'll be less pressure on the tire pressure gauge and the pressure on the tire.

Jam: Yeah. Yeah.

Melissa: And the thing that we have to describe that in chemistry is this formula that is pressure times volume

Jam: Okay.

Melissa: equals temperature.

Jam: Okay.

Melissa: And you may have heard that described as PVNRT or something like that. And that's because there's N is the number of molecules. So if you're holding the number of molecules, the same, the pressure and volume increasing is correlating to the temperature increasing. And then there's also R which is a gas constant that is too confusing for you to worry about right now. But if pressure and volume go up, temperature also goes up if temperature goes down, so does pressure and volume.

Jam: Got it. Got it.

Melissa: So that is, what's known as the ideal gas law.

If you had a perfect gas that was going to act exactly the way that we hope it would, you can apply this perfectly.

Jam: Yeah.

Melissa: In reality, gasses aren't ideal. And so there's probably some other things that happen, but this pressure times volume is roughly equal to temperature is still true. And you can see the tires deflate as the temperature goes down because of that. Now, if you want to do this at home and it's not super cold and you want to do it in a way that you can. If you blow up a balloon or because those are terrible for the environment, some other closed container that has flexible walls, like, I don't know a stasher bag might do this. Or if you have plastic bags that you can then reuse again and not only use once.

Jam: Yeah. yeah.

Melissa: an airtight container with somewhat flexible walls, you can fill it up with your breath or something else and stick it into the freezer and it should come out shrunken

compared to what it was when you put it in.

Jam: Yeah. Yeah. Interesting.

Melissa: Yeah. So you nailed it.

Jam: Wow. That's cool. Also it's, it's weird how some of this stuff starts to kind of make sense without knowing those equations or whatever. The number of things we've talked about that are just true of chemistry and how molecules behave in different situations. And then how it's like, oh, this seems like this would be what happens because we've known other ways to behave in other situations, but it's kinda crazy.

And also it is frustrating too,

you know, every winter it's like, man, I gotta go air these tires up, especially when you're in a hurry, which you and I both are a lot.

Melissa: A lot.

Jam: And it was like, you get in your car and then the lights on. And you're like, dang it

Melissa: Oftentimes I will ignore it and hopes that the temperature will heat back up And will even itself back out. Probably not the best policy, but it is something I sometimes do.

Jam: And people say the meantime, you're getting less good gas mileage.

Melissa: Yeah. And I've heard it kind of wears not, not as well on your tires.

Jam: That makes sense too.

Melissa: The other thing I wanted to say is this is kind of interesting to put right here in the middle of the coffee series, because it is the opposite of what happens to coffee when it's roasted.

Jam: Uh,

Melissa: roast the coffee and the water molecules are heating up.

And so they're putting more pressure and they're expanding until eventually the coffee bean can't hold it anymore. And it cracks.

Jam: Yeah,

Melissa: Your tires are experiencing the opposite thing where it brings it down and there's less pressure. And then they go a little flat. And I have also heard you're more likely to bust a tire in the summer because as extreme temperatures, heat up the gas in your tires, there's more pressure on them.

And then being on the road, you're just more likely to have a like burst tire in the summertime.

Jam: we had one time sort of the opposite problem happened, but I think it makes sense too, but we went, we drove from Texas, which sometimes in the winter, like we're in December right now and we have some pretty, you know, moderate weather.

Melissa: It was 80 degrees Fahrenheit this week.

Jam: So we drove up to Indiana and we arrived. It was, there was already lots of snow and it was continuing to snow.

And so our car had air that was at a pressure that was Texas temperatures. And then we went up all the way up to Indiana and our, I can't remember our actual gauge come on yet, or if it was not working correctly with that car we had at the time. But, uh, one of our tires ended up, um, Like we got a blow out basically.

And I think it was related because I couldn't find like a clear, like, you know, nail or I think it was already wearing anyway, but then it being flatter. And then I took the spare, the donut out of the back, and it was very flat because the air in it of course had the same problem. And we were able to get, put some air in it and stuff like that, but it was like a crash course in.

Melissa: Yes.

Jam: drastic differences of the temperature

Melissa: Yeah. And I'm sure the drastic difference, even just on the tire, going that quickly from one to another, probably it was difficult

Jam: Yeah. Yeah.

Melissa: Wow.

And I will say that's just something I've heard about the blowouts. That's not something that I know it's just something sort of chemistry off the cuff for you. So that's it. That's your little chemistry lesson that you can take with you a little snippet you can take with you into the winter months,

Jam: So normally at this point, I would explain back to you,

but I

Melissa: you started by knowing

Jam: by knowing, so do I get a pass? Like, do I.

Melissa: yes. You get a pass. You don't have to take the final exam because you succeeded in the earlier portion.

Jam: Very cool. That's great. Like what a first, I mean, there's a few times I've had a hypothesis going into that episode and I've shared isn't maybe this and it's not been, sometimes it's been partly right or on the right track or whatever, but this is the first time it's been pretty

Melissa: 100%. Yes. I'm so proud. I feel, I feel, I cannot describe the feeling of pride. I have like, wow. We did it. Jam used the things that we learned and talking about chemistry in everday life.. For the past two and a half years, once a week,

Jam: Yeah.

Melissa: and correctly made a hypothesis about the way molecules behave and the result of that in everyday life.

And it just him makes my little chemist hearts so happy. I'm so proud.

Jam: Well, speaking of you don't have to share this because. Well, you already did, but speaking of happy things, what in your week, this past week made you happy?

Melissa: Well, that was an amazing segue jam. Good job. I have R Oh this is a really good one. And I think it might help the listeners also, who feel similarly to me,

Jam: Okay.

Melissa: you know, a little bit about this Jam but my husband and I typically have had a big chore day on the weekend where we do our laundry and all of that.

And I was noticing that I was leaving the weekend, going into Monday, feeling like I didn't get to rest at all. It felt almost like I was just working.

Jam: yeah,

Melissa: And if we just had other events and we didn't do chores, then I was stressed, because I wouldn't have clean laundry or whatever. So I found this person on Tik TOK.

I think her name is Rosie. She's very popular on quote unquote, clean talk tech talks about how people clean. And she has a system she uses called the fly lady method and the system is. You simply do one load of laundry every day and you clean the hard surfaces to clean, like your bathroom counter is what I picked and your kitchen sink every day. And by doing that, your house stays at a higher level of cleanliness throughout the week. And you don't have, for me, the big draw was I don't have to spend a whole day doing laundry on the weekend. Instead I've spent 15 minutes doing laundry during the week.

Jam: yeah.

Melissa: And the laundry is done when you get to the weekend.

And so it doesn't matter if this weekend we spent the whole weekend with other people and I have clean clothes.

Jam: Yeah,

Melissa: It is very exciting. So we've implemented that in our home where it's, you know, a little bit different. She's a stay-at-home mom, I'm obviously a working non mom. So our schedules are very different, but.

Jam: she has more laundry to have to wrangle a little

bit, which yeah, I can relate to a little bit, but,

Melissa: and I think the way they divide the labor in their household, her husband's less involved because he's working in she's home. So it's a little

different, but

Jam: yeah,

Melissa: we adapted it to our system. We've been doing a little laundry every day and then just sitting and talking while we fold it, which is kind of Nice. And then, um, at the end of the day, we always make sure our sink is cleaned and we always make sure that the bathroom counter is wiped down and then our house stays clean. And then we just spend one hour cleaning on the weekend or at the Very beginning of the week to do those, those pesky tasks like cleaning the toilet, wiping down the shower, those kinds of things, vacuuming, mopping.

We do that and it only takes 45 minutes to an hour and it has worked out really well for us.

Jam: Nice.

That's awesome. Very cool.

Melissa: to encourage people. If they are feeling like they're spending their whole weekend cleaning and they don't know how else to fit it in, there are other ways. And you can email us if you want to hear more, because I love sharing about things that work well, for me.

Jam: Yeah. Yeah. There's definitely a way. There's a way

Melissa: there's a way.

Jam: to not hate your weekends.

Melissa: I know it's crazy. What a difference it's made for my whole work week. I start Mondays not feeling tired.

Jam: Yeah, that is

Melissa: So an E and it's given me more freedom to just randomly see friends because there's not so much chores that we have to do on the weekend.

Jam: That's great.

Melissa: So it's been very good. I strongly encourage you. And there's even more to the system that we haven't gotten into.

Like, you can do zones of deep cleaning, but we're just working the main system for now and it's made a world of difference.

Jam: That's awesome. Okay, cool.

Melissa: What about you Jam? Have you had a happy thing this week or thing that you want to share with the listener?

Jam: Yes, I do. I've thought at one just in time. So I, the day at my Thanksgiving time, week, whatever a few weeks ago was mostly busy, but not in a bad way, but, um, I had one day basically between that break ending and work, starting back. Where I had some time just to myself

Melissa: Wow.

Jam: and what I, it also happened to perfectly line up with the release of The Beatles: Get Back, documentary series.

Melissa: And you love a good documentary.

Jam: love a good documentary

Melissa: Also, you studied in school.

Jam: I studied in school and I love the Beatles and we don't talk about music a ton on here, but gosh I love me some Beatles. So I watched that basically over the course of a day and a half watched the entire series. And I had to take a lot of breaks because it's long. I mean like the episodes pretty long, but I would like watch half of one and then go do some stuff or whatever, but, oh my gosh, if you, uh, are a Beatles fan a little bit, you there's so many.

Little gems and little cool things in this documentary series. It's about, what's technically their final album that, that came out and they had a documentary crew following them and that they released an, um, film back in the day, back in 1969, just called Let It Be.. And it was, uh, it was not a bad movie, but it, it was very truncated, very compact.

Melissa: right. Cause it was Just a movie.

Jam: Just one. Yeah, short little, but there was about 60 hours of footage at about 150 hours of audio. And so Peter Jackson of Lord of the rings fame, uh, has spent like four

years. I spent like four years digging through all the stuff, syncing it all together and created this, this three part basic a trilogy, you know, the man loves trilogies and it is very interesting

Melissa: Wow. That's so cool.

Jam: So I watched that if you're someone who likes to Beatles and you have already watched it, please email us. I'd love to, you know, go back and forth and nerd out about it with you. Um, and if you haven't in that kind of thing interest, you definitely check it out. It's on Disney plus. Um, I wish I could just share my login with everybody so that you don't have to pay for anything if you don't already have it, but definitely check it out.

I think you will like it. And there's just something about the world of music and the world of me already liking documentaries. Coming together in that,

Melissa: that satisfied.

Jam: that one that's this series was like such a nice treat

Melissa: Well, that's a fun one.

Jam: yeah.

Melissa: That's a little, it's a little different than your usual ones. I loved that. That was a really fun,

Jam: Yeah. I can talk, I could talk all day about that. So that's why I was like, I gotta wrap this up. I've got to tell you guys just to email me so we can, we can nerd out about it

Melissa: that's fun. that's really fun jam. Thanks for sharing that. And thanks also for using your chemistry knowledge jam to predict how molecules will behave. That is my dream as a chemistry education person. Ah, what a delight.

So thanks for that. And thanks to all you listeners as well. We literally could not do this about it without you. This is such a fun thing that we get to do weekend and week out. And we. Really hope that you all have a great holiday, a safe holiday with your family, and we'll see you all back here. December 30.

Jam: And thank you for teaching us and for teaching us many, many chemistry lessons that have culminated in the ability. Guessed correctly about one of these. Um, and if you out there listener, have a question or an idea, or a thought about something chemistry related in your everyday life. Like this one, which is very everyday like, man, why are my tires flat?

Why is my pressure light on or whatever, then please reach out to us on Gmail, Twitter, Instagram, or Facebook at chemforyourlife that's chem F-O-R your life to share your thoughts and ideas. If you'd like to help us keep our show going and contribute to cover the cost of me. go to ko-fi.com/chemforyourlife and donate the cost of a cup of coffee. If you're not able to donate, you can still help us by subscribing on your favorite podcast, app and rating and writing a review on apple podcasts. That also helps us to share chemistry with even more people.

Melissa: This episode of chemistry for your life was created by Melissa Collini and Jam Robinson references for this episode can be found in our show notes or on our website. Jam Robinson is our producer, and we'd like to get a special, thanks to A. Kheawsang and N. Newell who reviewed this episode.

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