Winter tyre pressure

handlemaster

Whats the rule with winter tyre pressure is it .2bar over normal?

corkgsxr

No go normal, if I know it's going to be very icey I drop pressures.

Eg my standard is 55psi. I dropped to 40 psi

Saying that I'm mainly urban driving.

If I was driving on motorways etc I wouldn't drop it

handlemaster

And driving iin snow ?

slimjimmc

I'd just leave them at normal pressure, that's what they're designed for. They tend to have more flexible tread blocks and side walls anyways.

https://www.theaa.com/motoring_advice/safety/winter-tyres-in-the-uk.html

CiniO

handlemaster wrote: »

Whats the rule with winter tyre pressure is it .2bar over normal?

That's advised for driving in low temperatures.
If you are planning to drive in regions where it's going to be minus 20 deg. or lower, you might increase pressure by .2 bar to normal.

CiniO

corkgsxr wrote: »

No go normal, if I know it's going to be very icey I drop pressures.

Eg my standard is 55psi. I dropped to 40 psi

Saying that I'm mainly urban driving.

Why would you drop pressure for ice driving?
I though that this would reduce grip.

corkgsxr

CiniO wrote: »

Why would you drop pressure for ice driving?
I though that this would reduce grip.

Seems to work for me, and I'm in a big van so you'd notice

kavanada

You might lower the psi in icy conditions so the tyre width spreads out that bit more and is more flexible.

To overinflate would cause the tyre to ride on a narrower part (in the centre) and therefore lose grip.

As said above, this ain't the artic. Normal psi's are more than sufficient. People might top up the air due to it contracting at the colder temperature but all you're doing is raising it back up to the original psi.

bpmurray

I spent 10 years in Scandinavia and there's no doubt in my mind that your tyres should be correctly inflated to the pressures specified by the engineering teams who created them. In winter change to winter tyres if you expect winter conditions, but we don't get winter conditions in Ireland!

Do not over- or underinflate.

doctorchopper

kavanada wrote: »

You might lower the psi in icy conditions so the tyre width spreads out that bit more and is more flexible.

To overinflate would cause the tyre to ride on a narrower part (in the centre) and therefore lose grip.

As said above, this ain't the artic. Normal psi's are more than sufficient. People might top up the air due to it contracting at the colder temperature but all you're doing is raising it back up to the original psi.

I'd have to dissagree with you there, a narrower tyre is better for snow,slush and ice as it will cut down through the snow to find traction, you dont want to be floating on top of snow

seamusk84

corkgsxr wrote: »

No go normal, if I know it's going to be very icey I drop pressures.

Eg my standard is 55psi. I dropped to 40 psi

Saying that I'm mainly urban driving.

If I was driving on motorways etc I wouldn't drop it

55psi? That is really high, what do you drive?

tossy

doctorchopper wrote: »

I'd have to dissagree with you there, a narrower tyre is better for snow,slush and ice as it will cut down through the snow to find traction, you dont want to be floating on top of snow

There is a massive difference between a narrow tyre with all of it's effective tread making contact with the road and a tyre over inflated so that a narrower portion of it's effective tread pattern makes contact with the road. Over inflating a tyre so you get a narrower contact patch is not going to end well in any conditions.

doctorchopper

tossy wrote: »

There is a massive difference between a narrow tyre with all of it's effective tread making contact with the road and a tyre over inflated so that a narrower portion of it's effective tread pattern makes contact with the road. Over inflating a tyre so you get a narrower contact patch is not going to end well in any conditions.

I never said to over inflate the tyres, i'm just pointing out that a narrower tyre is better in snow,slush and ice and under inflating to make it wider is worse

tossy

doctorchopper wrote: »

I never said to over inflate the tyres, i'm just pointing out that a narrower tyre is better in snow,slush and ice and under inflating to make it wider is worse

You quoted a post from a member saying that to over inflate would narrow the tyre and lose grip, your opening line was "I have to disagree with you there"

doctorchopper

tossy wrote: »

You quoted a post from a member saying that to over inflate would narrow the tyre and lose grip, your opening line was "I have to disagree with you there"

Sorry my fault, i was un clear in my post, i just meant underinflating a tyre to make it wider would be worse as narrower tyres work better on the snow

corkgsxr

seamusk84 wrote: »

55psi? That is really high, what do you drive?

Nissan primastar. That's what the van asks for.

I think the rears are 60


Lately when we had snow. It was manageable but had to give up and go round some hills.
Came home, dropped pressures. Next morning in near as same conditions found it alot Easyer.

Renegade Mechanic

Keep your pressures normal, lads. Depressurising is a myth. Lowering them, widening the contact patch is what the iceladic fellas do for flotation over snow, deeper than the vehicles their driving, the entire thread forms over the uneven surface too. Not a small layer of snow/ice on a solid road. On a solid surface, you're still decreasing the contact patch because the middle of the tyre thread is pushed up from the unsupportive sidewalls. All youre doing is allowing the sidewall to flex more, letting the vehicle gain momentum against the tyres when changes in direction are made, increasing the risk of loosing grip.

As mentioned, narrower road tyres are more ideal here than the wider road tyres, common on modern cars/suvs.

Over inflation is just as bad, reducing the contact patch twice as much by lifting the edges away from the surface.

kavanada

Yes, I think there's a whole load of misunderstanding/misquoting going on here!

I incorrectly suggested/wrote that it's ok to lower your normal all season/winter tyre a few psi to flatten out the bottom to attain more grip. That was not what I had intended to imply and I think I mention such in my last paragraph in my previous post. I was thinking of the Top Gear Hilux which is not the same as doing 100km/h on the M50 at -2'C and 25psi.

My comment about adding air was in reference to a normally inflated tyre's air contracting on a cold day to give a lower psi than before.

I think, as mentioned by a previous poster, just pressurise your tyres to the recommended pressure. If it's icy, only studded tyres will give you the grip you're seeking. Not fiddling with the psi.

Hope I clarified/corrected my earlier post.

CJhaughey

Just to be clear as well, The contact patch does not widen with reduced air pressure it actually lengthens.
Back on topic, Winter Tyres should be run at the same pressure as summer tyres. Follow the manufacturers guidelines usually on a sticker in the glovebox, B Pillar or sometimes in the fuel cap.