Tyre pressure and temperature

Reallyretired

Reallyretired

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The target tyre pressure is only correct at around 20C so I found this chart useful for setting tyre pressures when the temperature is either cold like now or very much hotter as we hope to find when away.

SmartTireComp.jpg
 
You also need to take into account that tyre pressure increases as the tyres warm up. I always set tyre pressure a bit lower than needed as within a couple of miles it has risen to required pressure.
 
Polar bear said:
You also need to take into account that tyre pressure increases as the tyres warm up. I always set tyre pressure a bit lower than needed as within a couple of miles it has risen to required pressure.
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Don’t the people who recommend the tyre pressures take that into account I.e. stipulate the pressure when cold?
 
I think a few heads may explode if we add 'define cold' into the tyre pressures debate 😂😂

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dunnah01 said:
I think a few heads may explode if we add 'define cold' into the tyre pressures debate 😂😂
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Maybe. That chart defines 'cold' as 18 degrees C (65 degrees F). That's why the line is highlighted, and you'll see the pressures are the same as the top line.
 
Don’t do this to me.........I still haven’t worked out what tyre pressures to run on in normal conditions! :oops: ;)
 
Nowadays lots of vehicles have TPMS fitted, so people notice the rise in pressure with temperature much more.

Suppose you start with a tyre inflated to the correct pressure at the manufacturer's stated temperature. It would help to have a chart that showed what the pressure would be if the temperature varied. If the tyre pressure stayed on the chart, no air has been lost or added, so no need to do anything. If the pressure is lower than the chart, then it needs topping up to whatever the chart says.

Here's a chart like the OP, but with a temperature column more like Northern Europe, less like Florida.
The 'cold' pressures are at 20 deg C (not 18 as in the OP).
TyrePressureVsTemp.jpg
 
Last edited:
This is the problem I’ve got.......at normal ‘cold’ pressures.

Fiat sticker on Van......Front 5bar (72.5) Rear 5.5bar (79.8).

Converters Owners Manual.......Front 4.75bar (69) Rear 5.5bar (79.8).

Continental Tyres........Front 3.75bar (54.4) Rear 5bar (72.5).

:unsure:
 
I just use the Continental tyre chart for the size and load rating of my tyres at my axle weight, or I did ;) but now in the new van I would if the TPMS allowed it so I am actually a bit over, over is better than under other than for your fillings but full air suspension sorts that out.

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autorouter said:
Nowadays lots of vehicles have TPMS fitted, so people notice the rise in pressure with temperature much more.

Suppose you start with a tyre inflated to the correct pressure at the manufacturer's stated temperature. It would help to have a chart that showed what the pressure would be if the temperature varied. If the tyre pressure stayed on the chart, no air has been lost or added, so no need to do anything. If the pressure is lower than the chart, then it needs topping up to whatever the chart says.

Here's a chart like the OP, but with a temperature column more like Northern Europe, less like Florida.
The 'cold' pressures are at 20 deg C (not 18 as in the OP).
View attachment 467333
Click to expand...
I don’t expect a problem with TPMS and cold tyres.
1) the tolerance set will be a range that covers most temperature changes.
2) The tyre material and core temperatures will soon warm up.

But in the UK maybe I’ve yet to get the cold & hot extremes to go out of range on all my vehicles I’ve owned with TPMS

My MH had a TyrePal fitted & I see the pressure & temps rise quickly before stabilising on a journey from cold.
 
funflair said:
I just use the Continental tyre chart for the size and load rating of my tyres at my axle weight, or I did ;) but now in the new van I would if the TPMS allowed it so I am actually a bit over, over is better than under other than for your fillings but full air suspension sorts that out.
Click to expand...

On the Continental Chart the rears aren’t too far apart, but the fronts are way down on the other two.

I’ve decided on a compromise......4.25bar front and 5bar rear.

Not got a factory fitted TPMS, so have just purchased a Tyrepal Solar.
 
Dumb newby question - is that telling me that I should let air out to get from 87psi back down to 80psi when it's 40C?
 
kevenh said:
I don’t expect a problem with TPMS and cold tyres.
1) the tolerance set will be a range that covers most temperature changes.
2) The tyre material and core temperatures will soon warm up.

But in the UK maybe I’ve yet to get the cold & hot extremes to go out of range on all my vehicles I’ve owned with TPMS

My MH had a TyrePal fitted & I see the pressure & temps rise quickly before stabilising on a journey from cold.
Click to expand...
I'm not suggesting it's a massive problem. However the tolerance range on the acceptable pressure is very wide. So if you get a slow puncture when the tyre is hot, it won't trigger the alarm until a lot of air has been lost.

An alert driver might notice the pressure was below 'normal' for that temperature. But if the MH is new to you, the 'normal' behaviour might be unknown to you. This chart tells you what is normal.

TPMS gives you the data to be able to see this kind of problem in its early stages, if you know what to look for
 
twbm said:
Dumb newby question - is that telling me that I should let air out to get from 87psi back down to 80psi when it's 40C?
Click to expand...
No, it's saying if you set the pressure to 80psi at 20C, then 87psi at 40C or 74psi at 0C is perfectly normal, and no air has been lost/added. No need to do anything.

Also if you're checking the tyre pressures at 0C, you should set them to 74psi, so that they are at 80psi at 20C.

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autorouter said:
No, it's saying if you set the pressure to 80psi at 20C, then 87psi at 40C or 74psi at 0C is perfectly normal, and no air has been lost/added. No need to do anything.

Also if you're checking the tyre pressures at 0C, you should set them to 74psi, so that they are at 80psi at 20C.
Click to expand...
Thank you.
 
Just to be clear, is the temperature we are discussing the ambient temperature in the shade or the actual tyre temperature?
 
Anyone have a copy of the continental chart they can share please? Or a link to it? Thanks in advance.
 

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