Hot weather and tyre pressures

[yorkslass]

I just wonder, does the hot weather affect tyre pressure. Do I need to increase/decrease the pressure slightly? I had a rear tyre blow a few years ago, and i'm not anxious to repeat the experience.

 

[maingate]

While overhauling my spare tyre carrier last year, I did a little experiment. It was a warm sunny day (but not really hot like now). I had put air in the spare, so knew the pressure. I put the tyre in the shade then rolled it out into the sunshine. After a short time the pressure had risen by 4 psi.

 

[harrow]

I just wonder, does the hot weather affect tyre pressure. Do I need to increase/decrease the pressure slightly? I had a rear tyre blow a few years ago, and i'm not anxious to repeat the experience.

Use a good quality pressure gauge and adjust the pressures when the tyres are cool, before you have driven on them.

 

[Wooie1958]

Use a good quality pressure gauge and adjust the pressures when the tyres are cool, before you have driven on them.

Agreed :dance:

 

[Full Member]

I just wonder, does the hot weather affect tyre pressure. Do I need to increase/decrease the pressure slightly? I had a rear tyre blow a few years ago, and i'm not anxious to repeat the experience.

As a tyre heats up so the pressure will increase, Sue. Having said that the effect is small for a tyre in the UK (even in current conditions) and probably about the sort of variation you'd get between pressure gauges anyway. Then if you factor in variations in tyre manufacture, tyre materials..........
Nothing to be concerned about in my view. Strangely enough I calculated the change in tyre pressure due to temperature variation for a member at Attleborough a couple of weeks ago. I'll run you over it at the next meet we're both at if that would reassure you. I promise the calculation is not difficult to follow.

Colin

 

[Full Member]

The difference caused by varying air temperature is smaller than the inaccuracy in your pressure gauge and the guesstimates of the correct pressure.

My car has a sticker showing the correct tyre pressure for the rear tyres.

The same tyres, in the same conditions, but with different loads and speeds, have recommended pressures varing from 29psi to 46psi.

Strange. I was typing pretty much the same at the same time as you, hairydog!

Colin

 

[maingate]

As a tyre heats up so the pressure will increase, Sue. Having said that the effect is small for a tyre in the UK (even in current conditions) and probably about the sort of variation you'd get between pressure gauges anyway. Then if you factor in variations in tyre manufacture, tyre materials..........
Nothing to be concerned about in my view. Strangely enough I calculated the change in tyre pressure due to temperature variation for a member at Attleborough a couple of weeks ago. I'll run you over it at the next meet we're both at if that would reassure you. I promise the calculation is not difficult to follow.

Colin

I presume you were applying Boyles Law.

How did you work out the Volume? Or did you leave it as a constant?

 

[Full Member]

I presume you were applying Boyles Law.

How did you work out the Volume? Or did you leave it as a constant?

It's generally attributed to Gay-Lussac and called Gay-Lussac’s Law, I believe, maingate, though many others contributed to what we now call 'The Gas Laws' - including, as you mention, Boyle.
I assumed constant volume. As you're aware, tyres are steel braced and I suspect the volume change is insignificant compared to the other variables involved.

Colin