Winter tyre pressures ?

[peter999]

Just bought my winter tyres and wheels (205/45 x 16") for the Mk2 vRS but does anyone know what pressures I should be using for these - or stay with the recommended ones for the original 205/40 x 17" tyres ?

[fabdavrav]

This my answer from another post onthe same topic

As we all know air expands with heat..........so as the tyre is used and gets warm the air inside warms up and expands so the internal pressure is now higher! Conversley as the the tyre cools the air in side contracts and thus the pressure lowers...........this happens with either the internal air temp or the external air temp!!!

From memory most of the manufactures tyre pressures (on the fuel filler cap) are quoted at 20C.......but there is roughly a 0.1bar pressure drop per 10C drop.....Proper calcs below!!

+20C = 68F say your cold tyre pressure is 2.1bar = 30.46psi

+10C = 50F now your tyre pressure is 1.98bar = 28.66psi

0C = 32F now your tyre pressure is 1.85bar = 26.86psi

-10C = 14F now your tyre pressure is 1.73bar = 25.06psi

-20C = -4F now your tyre pressure is 1.60bar = 23.26psi

I tend to lower the tyre pressure from the manufactures stated figure by 0.1bar per 10C drop.....but only realy start altering the pressures when the outside temps and the tyres are at a steady 0C! So at 0c I do not inflate my tyre to 2.1bar but to 1.9bar...this means that as the tyre heats up it will not be "over pressure" at the same hot temp as if I inflated the tyre to 2.1bar at 20C....

If I inflate the cold 0C tyre to 2.1bar (pressure for 20C) then when the air in the tyre gets to 40C the pressure will be 2.5bar!........If the tyre is at 2.1bar @20C as per the fuel filler cap then at 40C it will be 2.3bar........so a diff of 0.2bar!!!!!

These are my personal choices re tyre pressure.........most experts state don't mess with the tyre pressures to much (0.3bar at most from the manufactures).....it is very subjective as it affects feel and can alter from one tyre to the next!

P.S. I think that Skoda state + 0.2bar to their normal tyre pressures......but again note above comment^!

[Auric Goldfinger]

The wife's are set at 32 psi all round as recommended by my local tyre place (very reliable)

205/45/16 Goodyear GW3

[H17YD_L]

I've got some 185/55/15 winters to go on. I haven't got a clue what pressure i should put in them? Anyone know?

[fabdavrav]

I've got some 185/55/15 winters to go on. I haven't got a clue what pressure i should put in them? Anyone know?

Starting point is what is printed on the sticker on the inside of the fuel filler cap then alter up or down as per my previuos post!

[logiclee]

I've got some 185/55/15 winters to go on. I haven't got a clue what pressure i should put in them? Anyone know?

Your manual says to inflate winter tyres to the the same pressure as summer tyres +0.2bar.

Have a look in your fuel filler cap.

Cheers

Lee

[H17YD_L]

Does that apply even though my standard tyres are 205 40 17?

[john123]

This my answer from another post onthe same topic

As we all know air expands with heat..........so as the tyre is used and gets warm the air inside warms up and expands so the internal pressure is now higher! Conversley as the the tyre cools the air in side contracts and thus the pressure lowers...........this happens with either the internal air temp or the external air temp!!!

From memory most of the manufactures tyre pressures (on the fuel filler cap) are quoted at 20C.......but there is roughly a 0.1bar pressure drop per 10C drop.....Proper calcs below!!

+20C = 68F say your cold tyre pressure is 2.1bar = 30.46psi

+10C = 50F now your tyre pressure is 1.98bar = 28.66psi

0C = 32F now your tyre pressure is 1.85bar = 26.86psi

-10C = 14F now your tyre pressure is 1.73bar = 25.06psi

-20C = -4F now your tyre pressure is 1.60bar = 23.26psi

I tend to lower the tyre pressure from the manufactures stated figure by 0.1bar per 10C drop.....but only realy start altering the pressures when the outside temps and the tyres are at a steady 0C! So at 0c I do not inflate my tyre to 2.1bar but to 1.9bar...this means that as the tyre heats up it will not be "over pressure" at the same hot temp as if I inflated the tyre to 2.1bar at 20C....

If I inflate the cold 0C tyre to 2.1bar (pressure for 20C) then when the air in the tyre gets to 40C the pressure will be 2.5bar!........If the tyre is at 2.1bar @20C as per the fuel filler cap then at 40C it will be 2.3bar........so a diff of 0.2bar!!!!!

These are my personal choices re tyre pressure.........most experts state don't mess with the tyre pressures to much (0.3bar at most from the manufactures).....it is very subjective as it affects feel and can alter from one tyre to the next!

P.S. I think that Skoda state + 0.2bar to their normal tyre pressures......but again note above comment^!

........great guide thanks