Tyre pressure varying temperatures

Tyre pressure varying temperatures

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Discussion

mawallace

Original Poster:

184 posts

80 months

Sunday 21st October 2018
quotequote all
At the moment the tempature varies during the day. E.g. it's 5 degrees this morning and now it's 19!

Tyre pressure varies on temperature so I was thinking. If I check them first thing, when it's 5 degrees, the pressure will be higher later on, so they will be overinflated.

So is it better to have overflated tyres or underflated by having the correct temperature at 15 degrees

TooMany2cvs

29,008 posts

133 months

Sunday 21st October 2018
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How regularly do you get your pressure gauge recalibrated?

I'm assuming you must do, if such tiny changes in pressure are important to you...

Pica-Pica

14,479 posts

91 months

Sunday 21st October 2018
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Read handbook and follow tyre label pressure guide. The manufacturers have done all the worrying for you.

waremark

3,256 posts

220 months

Sunday 21st October 2018
quotequote all
Pica-Pica said:
Read handbook and follow tyre label pressure guide. The manufacturers have done all the worrying for you.
Not so. They just tell you to test the pressures when the tyres are cold. They don't tell you how cold.

The variation with temperature is quite considerable - the inaccuracy of tyre gauges would not be significant. You become aware of this if your car has a pressure display. If one side of the car has been in the sun and not the other for example there is a really significant difference in pressure.

Jadatis

29 posts

196 months

Sunday 21st October 2018
quotequote all
Advice pressure cold should be calculated back to 18 degr C/ 65 degr F.
So dont lower it when outside temp is fi 30 degr C. Then cooling down of tyre is worse so the tyre needs the lesser deflection, the higher pressure gives, so lesser heatproduction.
When its colder outside fi 5 degr C , the other way around, but then you could use same pressure as for 18 degrC. For fuelsaving .

mawallace

Original Poster:

184 posts

80 months

Monday 22nd October 2018
quotequote all
A couple of articles here:-

https://www.tyresizecalculator.com/tyres/tyre-pres...

where the test show that the pressure change for 10 degree C the change was 1.5 psi.

https://www.driverknowledgetests.com/resources/how...

which claims that a 10 degree difference will change the pressure by 1.9 psi.


Kawasicki

13,471 posts

242 months

Monday 22nd October 2018
quotequote all
Tyre pressure gains due to ambient temperature are expected customer usage. The fact that you consider it already means you are the type of customer that is not going to drive around on grossly under or overinflated tyres. So worry less.

I don’t like setting pressures when one side has been in the sun and the other side the shade, so I’ll give you that!


waremark

3,256 posts

220 months

Monday 22nd October 2018
quotequote all
mawallace said:
A couple of articles here:-

https://www.tyresizecalculator.com/tyres/tyre-pres...

where the test show that the pressure change for 10 degree C the change was 1.5 psi.

https://www.driverknowledgetests.com/resources/how...

which claims that a 10 degree difference will change the pressure by 1.9 psi.
So if you set your pressures in August at 25 degrees, on a cold morning last week they would be 4 psi lower? That's why I got a low tyre pressure warning on Wednesday.

roadsmash

2,627 posts

77 months

Monday 22nd October 2018
quotequote all
mawallace said:
At the moment the tempature varies during the day. E.g. it's 5 degrees this morning and now it's 19!

Tyre pressure varies on temperature so I was thinking. If I check them first thing, when it's 5 degrees, the pressure will be higher later on, so they will be overinflated.

So is it better to have overflated tyres or underflated by having the correct temperature at 15 degrees
I bet you’re fun at parties.

Superleg48

1,525 posts

140 months

Tuesday 23rd October 2018
quotequote all
Jadatis said:
Advice pressure cold should be calculated back to 18 degr C/ 65 degr F.
So dont lower it when outside temp is fi 30 degr C. Then cooling down of tyre is worse so the tyre needs the lesser deflection, the higher pressure gives, so lesser heatproduction.
When its colder outside fi 5 degr C , the other way around, but then you could use same pressure as for 18 degrC. For fuelsaving .
Sorry....what?

Kccv23highliftcam

1,783 posts

82 months

Thursday 1st November 2018
quotequote all
roadsmash said:
mawallace said:
At the moment the tempature varies during the day. E.g. it's 5 degrees this morning and now it's 19!

Tyre pressure varies on temperature so I was thinking. If I check them first thing, when it's 5 degrees, the pressure will be higher later on, so they will be overinflated.

So is it better to have overflated tyres or underflated by having the correct temperature at 15 degrees
I bet you’re fun at parties.
Once upon a time I was "responsible" for a units MT preparedness for deployment.

Our main operating area was to be Norway.

The man makes a valid point.

Nickjd

208 posts

213 months

Saturday 3rd November 2018
quotequote all
Kccv23highliftcam said:
roadsmash said:
mawallace said:
At the moment the tempature varies during the day. E.g. it's 5 degrees this morning and now it's 19!

Tyre pressure varies on temperature so I was thinking. If I check them first thing, when it's 5 degrees, the pressure will be higher later on, so they will be overinflated.

So is it better to have overflated tyres or underflated by having the correct temperature at 15 degrees
I bet you’re fun at parties.
Once upon a time I was "responsible" for a units MT preparedness for deployment.

Our main operating area was to be Norway.

The man makes a valid point.
And manufactures do actually have variances in the "same" tyre for certain markets. However, unless you are going to be setting your tyre pressures every time you drive and also hourly as you drive, I wouldn't over think it. Does anyone pump their tyres up if they are going to drive after the sun has gone down or stop to put more air in if it starts to rain?

Onehp

1,617 posts

290 months

Wednesday 7th November 2018
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Don't worry, the main danger is as said massive over or under inflation which is problematic. Just follow the recommendation, check tyre pressures monthly when cold and adjust accordingly, and you're good. Generally there is a different recommendation for light load and high load, I haven't met many people who adjust for that... I would generally recommend to put pressures inbetween.

That said, if you're really into cars it can be a matter of preference to run a bit higher or lower than recommended pressure, perhaps within the width that the low and high load recommended pressures allow.

Higher end: less rolling resistance, more direct feedback, less comfort, less aquaplaning
Lower end: more grip, more comfort

I'm fairly extreme, using tyres with a sporty construction (PSS) and a lot of toe (out front, in rear) so this helps feedback and also tends to warm the tyres a bit more, so run relatively low pressures for better grip and comfort (harder bushes present).

Using aftermarket TPMS, I always see what is happening. When it's 5 degrees like now my tyres are at 2,1bar cold, once driving they increase to 2,2-2,3bar, which is where I want to be for more (wet) grip. In summer, pressure increases so I lower pressures a bit so it is 2,2bar at 20 degrees, once driving they tent to sit at 2,4bar. Which is the pressure that works for me*, but this is 0,5-0,7 bar under the recommended front pressures cold... but it works better for me.

  • after a hard drive, I check that I haven't been running on the sidewalls in the curves... all depends on the car, the tyres and the geo you're running.

RobM77

35,349 posts

241 months

Wednesday 7th November 2018
quotequote all
This is indeed a very valid point - the variation in pressure is quite large at this time of year. I err on the side of over inflation, so in a temperature range of 3 to 13 degrees, I set them accurate at about 5/6 degrees. You've also got to consider when you drive - like most people I commute 8-9am and then 6:30-7:30pm, so I avoid the warmest part of the day anyway.