Any - Checking Tyre Pressures in Cold Weather

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Sun 5 Jan 2014 11:24
Any - Checking Tyre Pressures in Cold Weather - csgmart

The temperature outside is something like 5 degrees C at the moment and I've just checked the tyre pressures on 3 vehicles. All show much less pressure on the gauge I am using (manual type) than the handbook recommends.

2 of the vehicles are fited with TPMS and neither vehicle is reporting low tyre pressure. The lower than expected reading is consistant - e.g. when it should be 38 psi I am getting a reading of 35 psi on every occasion I check.

Question - is it the gauge that is wrong or is the cold weather to blame (or both)?

Interestingly I Googled this question and all I could find was reference to checking the tyre pressures when the tyres were cold but nothing about the ambient air temp being below a certain figure.

I was once told that tyre pressures should ideally be checked when the air temp is around 15 to 18 degrees C. Not sure if that is good advice or bad.

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Sun 5 Jan 2014 11:33
Any - Checking Tyre Pressures in Cold Weather - RT

For a constant volume, pressure goes up/down with temperature.

Tyre pressures should checked when the tyres are cold - that does involve changes with the seasons.

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Sun 5 Jan 2014 12:35
Any - Checking Tyre Pressures in Cold Weather - Ordovices

A rough guide (v rough) is that a 20 degree (C) change would cause a pressure drop/increase of 3 psi.

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Sun 5 Jan 2014 14:23
Any - Checking Tyre Pressures in Cold Weather - misar
Interestingly I Googled this question and all I could find was reference to checking the tyre pressures when the tyres were cold but nothing about the ambient air temp being below a certain figure.

Just Googled and found plenty of advice re ambient air temp. For example:

www.goodyear.com/cfmx/web/corporate/media/news/sto...1

www.tirebuyer.com/education/tire-inflation-pressur...9

The manufacturer quotes pressures for (cold) tyres at the ambient air temperature on the basis that they will run hotter and pressure will increase. The premise is that the increase in operating pressure is much the same wherever you start (unless, eg you drive out of a freezer into a hot sunny day). Hence, you should always set pressure to the recommended value and adjust up or down as necessary when there are significant changes in ambient temperature.

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Sun 5 Jan 2014 15:40
Any - Checking Tyre Pressures in Cold Weather - focussed

I tried checking the tyre pressures when the car had been standing with the sun on one side only. The sunny side tyres were 3 psi more than the shady side -what to do?

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Sun 5 Jan 2014 16:03
Any - Checking Tyre Pressures in Cold Weather - RT

I check my tyre pressures only on cloudy days - not difficult in the UK !

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Mon 6 Jan 2014 12:56
Any - Checking Tyre Pressures in Cold Weather - Andrew-T

I tried checking the tyre pressures when the car had been standing with the sun on one side only. The sunny side tyres were 3 psi more than the shady side -what to do?

Nothing. While the car is stationary it doesn't matter, and once you are driving the tyres will warm up (front probably more than rear) and you may not be able to keep the same side permanently in the sun.

I have checked my tyre pressures every week or two for more years than I can remember, and have been surprised by the noticeable drop when winter arrives. I keep the pressure of 'cold' tyres close to the recommended figure, which may mean adding, or occasionally releasing, 2 or 3 psi.

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Sun 5 Jan 2014 18:11
Any - Checking Tyre Pressures in Cold Weather - csgmart
Interestingly I Googled this question and all I could find was reference to checking the tyre pressures when the tyres were cold but nothing about the ambient air temp being below a certain figure.

Just Googled and found plenty of advice re ambient air temp. For example:

www.goodyear.com/cfmx/web/corporate/media/news/sto...1

www.tirebuyer.com/education/tire-inflation-pressur...9

Saw these but I only work in degrees C not F..... I could do the calculation but was surprised there was no definitive UK source of advice.

Edited by csgmart on 05/01/2014 at 18:11

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Mon 6 Jan 2014 23:23
Any - Checking Tyre Pressures in Cold Weather - Andrew-T

< Saw these but I only work in degrees C not F..... I could do the calculation but was surprised there was no definitive UK source of advice. >

For the precision needed to set your tyre pressures, assuming that 1 C° equals 2 F° will be quite good enough. The practical difference between 34 and 36 psi (for example) is negligible.

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