Wheels/Tyres: Winter tyre pressures?

[ally]

Hi all
I read on a tyre review site where one person had written a review stating that winter trye pressures should be higher than normal pressures for the same sized tyre, is this right? He said there was a marked improvement with the higher pressures.
What pressures would you recommend to run with 235/60/18 winter tyres?

TIA

[wimorrison]

Originally Posted by ally

Hi all
I read on a tyre review site where one person had written a review stating that winter trye pressures should be higher than normal pressures for the same sized tyre, is this right? He said there was a marked improvement with the higher pressures.
What pressures would you recommend to run with 235/60/18 winter tyres?

TIA

The reality is that you will have to add more air to maintain the same pressure.

Boyles and Charles law combine into the Ideal Gas Law which states that PV=nRT This can be simplified for the purposes of this discussion to PV=T, where it is easier to see that as temperature goes down the pressure goes down for the same volume, therefore you will need to add more air to maintain the same pressure as the tyre volume remains the same.

As for increasing pressure for the winter, never heard of this.

[JimG]

I thought it was because the tyres were of a softer compound, so you have to have a higher pressure to maintain normally handling?

I would run them at eco pressure throughout the year, and only drop them to maybe 34-36psi in snow.

Just a guess. I'm sure Roy and other others with winter tyres will know.