Hallo all. On my way back home a while ago I stoped at the petrol station to refuel and I decided to check tyre pressure. I topped the tyres with air up to the recommended pressure, but when I arrived home I had an epiphany: It is -7C out there and I tped the air up as normal. Given that air will be somehow more dense now that the temperature is so low, will I have a problem with over inflated tyres when the weather warms up? I do not want to end up with massively over inflated tyres. Any help is appreciated. Many thanks.

Don't forget that if you drive more than 2 Km or so, flexing of the tire will increase the temperature, which increases pressure. Thus, pressures should be evaluated when the tires are "cold" (out of the sun, and stationary for a reasonable amount of time).

As the ambient temperature increases, so will the pressure within your tires. Hence the reason that you should check your pressures on a weekly basis, or when there are significant ambient temperature fluctuations. Of course you could send yourself to the loony bin checking pressures several times a day (due to day/night changes), or simply check them once weekly and know that you are at least ahead of approximately 98% of the populous who drive.

The quality and calibration of your pressure gauge can't be understated. I just sent my gauge back to the manufacturer for recalibration. It was found to be 8Lbs off.

zoey wrote:

Don't forget that if you drive more than 2 Km or so, flexing of the tire will increase the temperature, which increases pressure. Thus, pressures should be evaluated when the tires are "cold" (out of the sun, and stationary for a reasonable amount of time).

As the ambient temperature increases, so will the pressure within your tires. Hence the reason that you should check your pressures on a weekly basis, or when there are significant ambient temperature fluctuations. Of course you could send yourself to the loony bin checking pressures several times a day (due to day/night changes), or simply check them once weekly and know that you are at least ahead of approximately 98% of the populous who drive.

The quality and calibration of your pressure gauge can't be understated. I just sent my gauge back to the manufacturer for recalibration. It was found to be 8Lbs off.

The rule of thumb is for every 10° Fahrenheit change in air temperature, your tyre's inflation pressure will change by about 1 psi (up with higher temperatures and down with lower).

So working in Centigrade if it warmed up from -7 degrees C to +4 degrees C you would have an extra 2psi. Nothing too much to worry about for a few days.

zoey wrote:

Don't forget that if you drive more than 2 Km or so, flexing of the tire will increase the temperature, which increases pressure. Thus, pressures should be evaluated when the tires are "cold" (out of the sun, and stationary for a reasonable amount of time).

As the ambient temperature increases, so will the pressure within your tires. Hence the reason that you should check your pressures on a weekly basis, or when there are significant ambient temperature fluctuations. Of course you could send yourself to the loony bin checking pressures several times a day (due to day/night changes), or simply check them once weekly and know that you are at least ahead of approximately 98% of the populous who drive.

The quality and calibration of your pressure gauge can't be understated. I just sent my gauge back to the manufacturer for recalibration. It was found to be 8Lbs off.

psyxologos
LR recommend the following above / below a mean temperature of 20°C / 68°F:

When any decrease or increase in temperature above /below that datum point occurs then the tyre pressures should be adjusted by: 0.14 Bar, 14 kPa, or 2 lb Psi., for each 10°C (20°F) change. Increase pressures when the ambient temperature drops below 20°C / 68°F and decrease pressures when the temperature rises above that point.

So what you can determine here is that there is a reasonable safe margin for correct tyre pressures during changes in the ambient temperature on any given day and it is generally not necessary to continually change your tyre pressure.

As stated in previous posts, firstly get yourself a decent accurate tyre pressure gauge, then check your tyre pressures after the car has been standing (for example at least an hour) and then recheck on a weekly basis or when you move into a totally different climate regime i.e. you go on holiday from UK to Greece in August or from UK to Siberia in winter.

dont forget that the compresor will warm the air slightly as it passes thru the pump, the very act of compressing something causes heat At work
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yep I always go a psi or 2 over, leave them and use a guage after and leak a bit out until its ok. I really do have too much time on my hands on a morning 1  The missus - SD4 HSE - Black - 2012
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