Do tyre pressures go down when it's cold? (1 Viewer)

[BobtheBass]

Possibly a silly question, but we all know tyre pressures go up when the tyre is hot but do they go down when it's cold? I checked the pressures on mine today and they were all 3-5 psi down from last week. It was freezing cold though!

 

[Clarky]

Yes.
.
.
.
.
.
I think.

Richard.

 

[Wagoneer]

Recommended tyre pressures are based on an ambient air temperature of around 20 degrees C.

So, yes, they will reduce when the air temperature is less, but I guess this is allowed for in the 20C recommended setting.

I wonder what they use in places like Iceland where the temperatures are generally much lower.

Interesting question

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[WhiteCheyenneMan]

Absolutely! You need to adjust pressures at least twice a year, picking a suitably warm day and a suitably cold day to get it right. If you have something like TyrePal pressure monitoring, it will soon start bleeping if you don't. The variation by season is significant enough to affect wear, tear and handling.

 

[daveinspain]

Travelling from Spain to UK in summer (July/August) my tyre pressures usually drop by around 5 psi - and, of course, rise by the same amount going from UK to Spain.

 

[Peter JohnsCross MH]

Possibly a silly question, but we all know tyre pressures go up when the tyre is hot but do they go down when it's cold? I checked the pressures on mine today and they were all 3-5 psi down from last week. It was freezing cold though!

Your nuts do so why should'nt the tyres.......................

Yes as air expands and contracts (cold) due to temperature

Peter

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[SpeedyDux]

Possibly a silly question, but we all know tyre pressures go up when the tyre is hot but do they go down when it's cold? I checked the pressures on mine today and they were all 3-5 psi down from last week. It was freezing cold though!

*Anorak alert*

The tyre temperatures on my MH a minute ago were 11c offside, 8c nearside. That's more significant than just the ambient air temperature because direct sunlight also affects tyre temperature and consequently tyre pressure. Before I check the tyre pressures I check that they are all the same temperature.

 

[OldAgeTravellers]

Another interesting point is that apart from the pressure going up and down significantly with temperature, the tyres also only go flat at the bottom for some reason, or mine do anyway.
Steve

 

[Mr Chrysalis]

Yes. Here's the Physics:
Gay-Lussac's Law shows the relationship between the Temperature and Pressure of a gas. At a fixed volume, the temperature and pressure of a gas are directly proportional to each other. Since temperature and pressure have a direct relationship, if the pressure goes up then the temperature goes up and if the temperature goes down then the pressure goes down (and vice versa)

The equation for Gay-Lussac's Law is:

T1 = Initial Temperature (Kelvin - K)

P1 = Initial Pressure (atm or mmHg)

T2 = Final Temperature (Kelvin - K)

P2 = Final Pressure (atm or mmHg)

Note: Temperature must be in Kelvin for the equation to work. You calculate Kelvin temperature by adding 273 to the Celsius temperature.

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[Bognor Saint]

We've got tyre pressure sensors in our cars and know when the weather has got cold, flashing warning displays saying the pressure has dropped below acceptable minimum.
I wonder how many drive around with under inflated tyres.

 

[mikebeaches]

Yep, tyre pressure monitor on the car went off this morning. Only got the vehicle in May, and today was our first sharp frost, so time to pump the tyres up.

 

[Rapido925M]

The equation for Gay-Lussac's Law is:

T1 = Initial Temperature (Kelvin - K)

P1 = Initial Pressure (atm or mmHg)

T2 = Final Temperature (Kelvin - K)

P2 = Final Pressure (atm or mmHg)

Note: Temperature must be in Kelvin for the equation to work. You calculate Kelvin temperature by adding 273 to the Celsius temperature.

So if the temp goes from 17degC (=290K) to 27degC (=300k) it represents a change of 10/300 = 3% (approx).

If your tyre pressures are nominally 60psi, a 3% change is 2psi.

That is within the range of inaccuracy of most tyre pressure gauges, especially those analogue ones in garages .

Hence, I wouldn't worry about it - Gordon

PS My brother checks (and changes) his tyre pressure every trip, depending on how many passengers he has in his car. I keep telling him that life is too short

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[42208]

So if the temp goes from 17degC (=290K) to 27degC (=300k) it represents a change of 10/300 = 3% (approx).

If your tyre pressures are nominally 60psi, a 3% change is 2psi.

That is within the range of inaccuracy of most tyre pressure gauges, especially those analogue ones in garages .

Hence, I wouldn't worry about it - Gordon

PS My brother checks (and changes) his tyre pressure every trip, depending on how many passengers he has in his car. I keep telling him that life is too short

Could not agree more

 

[Taran_Las]

Another interesting point is that apart from the pressure going up and down significantly with temperature, the tyres also only go flat at the bottom for some reason, or mine do anyway.
Steve

Does that also apply in Australia?

 

[Enword]

So if the temp goes from 17degC (=290K) to 27degC (=300k) it represents a change of 10/300 = 3% (approx).

If your tyre pressures are nominally 60psi, a 3% change is 2psi.

That is within the range of inaccuracy of most tyre pressure gauges, especially those analogue ones in garages .

Hence, I wouldn't worry about it - Gordon

PS My brother checks (and changes) his tyre pressure every trip, depending on how many passengers he has in his car. I keep telling him that life is too short

My (HiFi) mate brought some floor standing speakers down to us from Romford, before he set off on the return trip he asked to use my pressure gauge as he'd increased the rear tyre PSI to compensate for the extra weight & wanted to reduce it before leaving, I just laughed & said, so when we were at your's last time did you do the same when all four of us went out for a meal? he looked sheepishly at me & said "Tosser" I think that was a No

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[Mr Chrysalis]

Does that also apply in Australia?

I've never been but pretty sure that they would only go flat at the top in Australia. This is because the water goes down the plug hole anti-clockwise there

 

[Taran_Las]

I've never been but pretty sure that they would only go flat at the top in Australia. This is because the water goes down the plug hole anti-clockwise there

Exactly! My rationale too

 

[ramsthom]

Is it really necessary to adjust pressures when it gets colder. If the correct pressures are set at say 20 deg c then in the summer when temperatures and pressures are higher I would not adjust the pressures to a lower level.

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[Pete5996]

If the TP's were set at an ambient temp of 20c and the temp drops, they'll lose a bit of pressure. However, as soon as you start driving they'll warm up so I wouldn't adjust them.

 

[Bailey58]

Your nuts do so why should'nt the tyres.......................Yes as air expands and contracts (cold) due to temperature Peter

Blimey so not only do we have to check the tyres but the nuts too, is that in case they fall off?

 

[Stretto Boy]

Yes. Here's the Physics:
Gay-Lussac's Law shows the relationship between the Temperature and Pressure of a gas. At a fixed volume, the temperature and pressure of a gas are directly proportional to each other. Since temperature and pressure have a direct relationship, if the pressure goes up then the temperature goes up and if the temperature goes down then the pressure goes down (and vice versa)

The equation for Gay-Lussac's Law is:

T1 = Initial Temperature (Kelvin - K)

P1 = Initial Pressure (atm or mmHg)

T2 = Final Temperature (Kelvin - K)

P2 = Final Pressure (atm or mmHg)

Note: Temperature must be in Kelvin for the equation to work. You calculate Kelvin temperature by adding 273 to the Celsius temperature.

Not as easy as just inflating to the recommended pressure then.

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[pappajohn]

The variation by season is significant enough to affect wear, tear and handling.

So why don't vehicle manufactures stipulate a summer and winter pressure instead of saying check pressures when tyres are cold.

 

[pappajohn]

I put wind in mine if they look a bit flat

 

[klaatu]

They warm up when you’re driving, though, don’t they?

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[dave newell]

Of course tyre pressures vary with temperature. Do you need to adjust them for summer and winter? NO! But you do need to check them regularly, at least monthly, preferably weekly and definitely before any journey.

D.

 

[PeteH]

According to my Tyrepal sensors. We Started yesterday 58psi(F) 70psi(R). Leaving S-Shields, by the time we hit the A19, they where up to 61(F) and 74(R) and stayed that way until Home. I did get a "warning" Beep (several) but that was the F-N/S battery is low and due changing. I am lowering the "cold" pressure by 1-2psi progressively in order to find the best "comfort" (Ride) whilst maintaining stability and consistent Temp/Pressures.

 

[Enword]

Blimey so not only do we have to check the tyres but the nuts too, is that in case they fall off?

Harley riders have to check for loose nut's I'm told

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[PhilG]

Temperature affects pressure , a lot. On the bikes we set base pressure cold, and then measure it again when the warmers come up to temperature, that will make 3-4psi more, even with pressure as low at 23psi.

For your MH, set them in the spring, and reset them for the winter.

 

[two]

*Anorak alert*
Before I check the tyre pressures I check that they are all the same temperature.

How do you measure the temp?

 

[Just smiffy]

It’s a natural phenomenon, when it’s cold the tyre pressure goes down and naturally gives you more grip
in the wet and cold... see, nature looks after you,.... naturally.....

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