Michelin tyre pressure advice (Winter)

[Marco34]

This one really confused me, it's direct from Michelin website.. read on......

Inflating tyres in winterhttp://www.michelin.co.uk/uk/images/1x1_transparent.gifWhen it's cold, tyre pressure registered on a pressure guage can seem lower than it really is.
For example, if a tyre is inflated to 2 bars at an ambient temperature of 20°, the pressure can read 1.9 bars on a manometer in an ambient temperature of 8°C.

This phenomenon can be misleading, and does not necessarily indicate that the tyre is under-inflated. It is not therefore worth inflating your tyres more in winter.

Surely if the outside temperature has dropped the tarmac is cold and thus the tyres will no get up to summer operating temperatures. I've read the opposite if anything; inflate a little more in Winter... I'm a little confused about Michelin's claim.

If it's say 7c outside I would inflate to 34psi as I would if it was 20c! Anyone have any thoughts on this? :confused:

Cheers
Marco

[faticus]

Hi Marco34,
i`m with you on this one, if the tyre side wall says inflate to xxxx pressure then this means all year round !!!!!!!!!!!!!!:beerchug:

[bora(ing) nick]

The cold air is more dense than the warm air of when the tyre is in use.....

As the tyres do there job they heat up, and in turn, the air inside expands, increasing the pressure inside the tyre to it's normal running temp and pressure.

If your staring from cold, the air will heat up more and thus expand more.

Well, thats my opinion of it anyway!

Nick

[RickT]

I would say just put what ever PSI you normally put in and take it from there...

Thats what i do anyway..

Rick

[rush]

Im with marco34/ faticus on this one.The information on the sidewalls is there for a reason.
Tyre companies spend millions every year on R and D for good reason.
They want us to buy the products they manufacture,if they dont work we dont buy
Speed ratings are important with different vehicles/conditions etc.
To be honest I choose the make first and buy the best I can afford (a nice tread pattern always helps)
One final thing always warm them up first IT MAKES SENSE:biglaugh:

[onzarob]

Inflating tyres in winterhttp://www.michelin.co.uk/uk/images/1x1_transparent.gifWhen it's cold, tyre pressure registered on a pressure guage can seem lower than it really is.
For example, if a tyre is inflated to 2 bars at an ambient temperature of 20°, the pressure can read 1.9 bars on a manometer in an ambient temperature of 8°C.


Guys I think you missed the important bit, when its cold the gauge under reads, nothing to do with air temp in tyre etc etc.it just 20psi will read 19psi on the gauge;)

but i wouldn't worry to much, as pertol station air pumps can be at least 1 psi out:D

[faticus]

onzarob, hi do you really believe the gauges on petrol forecourts ?????????? personally i use a digital one from halfords- does me-34psi in winter or summerhttp://www.vwaudiforum.co.uk/forum/images/icons/icon7.gif. not a tyre fitter so don`t know the technical ins n outs of this :beerchug:

[onzarob]

onzarob, hi do you really believe the gauges on petrol forecourts ?????????? personally i use a digital one from halfords- does me-34psi in winter or summerhttp://www.vwaudiforum.co.uk/forum/images/icons/icon7.gif. not a tyre fitter so don`t know the technical ins n outs of this :beerchug:

Generally no...some I do but thats because I double checked them with my gauge;)

[Marco34]

Guys I think you missed the important bit, when its cold the gauge under reads, nothing to do with air temp in tyre etc etc.it just 20psi will read 19psi on the gauge;)

but i wouldn't worry to much, as pertol station air pumps can be at least 1 psi out:D

A gauge should read the same weather it's at -20 or +20 surely. The mechanics of a gauge shouldn't change. I use a halfords dial gauge, very accurate. Michelin's point is that the air inside a tyre is the same at 20 or 7c. The molecules are cooler at 7c so less in size. If my tyre got to the same temps as they do in summer then the inflation would be the same. I agree on that, but, with cold air temps and cold tarmc my tyres only gain 2 psi on a run unlike 3-4 in summer.