S2 winter tyre pressure

[charles.y]

Just wonder should the S2 tyre pressure different from summer ones? Mine one is a S2 cab.
Is setting 33 front and 36 rear too low?

 

[xenon]

Sounds about right. There is no difference between settings in summer or winter - unless you use both summer and winter tyres as in Switzerland, for example.

 

[Alpine]

I run 32 psi on all 4 wheels on mine, all year round

 

[peanut]

tyre manufacturers recommend increasing pressures by 3lbs for sustained high speeds, so this time of year it might be advisable to reduce pressures slightly.
it would be interesting to take a poll

 

[pauljmcnulty]

ORIGINAL: peanut

tyre manufacturers recommend increasing pressures by 3lbs for sustained high speeds, so this time of year it might be advisable to reduce pressures slightly.
it would be interesting to take a poll

To me, with absolutely no mechanical experience whatsoever, and a "B" in O-Level physics in 1982......[&o]

If you're doing full-speed on an autobahn then the tyre temp will increase, and pressure with it. Why do they suggest adding pressure? I guess that a "softer", or under-inflated, tyre is as bad, as the friction of the moving rubber adds heat, but that would mean seriously low starting pressures.

If you've got 5 people and their luggage add pressure. Otherwise you'll be riding on the rims.

On wet or slushy roads, thinner tyres are better. Tread depth being equal. So, if you reduce pressure you get wider tyres and more aquaplaning?

Off-road, or on snow, you want to be "floating" above the surface and not getting bogged down. So, reduce pressures.

Now correct me! [8|]

 

[xenon]

Well you add pressure at higher speeds to reduce sidewall flex which is the major contributor to the heating of the tyre carcass. With UK tyres which are year-round tyres (as opposed to winter and summer tyres available elsewhere in the world) then the tyre pressures do not need adjusting because of variations in the weather.

 

[peanut]

ORIGINAL: xenon

With UK tyres which are year-round tyres (as opposed to winter and summer tyres available elsewhere in the world) then the tyre pressures do not need adjusting because of variations in the weather.

not according to the people who make the tyres . They recommend increasing pressures for 'sustained high speed driving' by that I presume they mean autobahns and motorways .
Its interesting to note that we appear to be running our tyres at wildly different pressures varying by as much as 4lbs and 3lbs difference between front and back.
I think most of us don't really take much note of tyre pressures which is surprising really as they make a huge difference to handling on a performance car. Worth doing a bit of research maybe

 

[xenon]

Sustained high speed driving yes - that's what I said and agreed with. I said they don't need adjusting for variations in the weather.

and they don't.

 

[peanut]

ORIGINAL: xenon

Sustained high speed driving yes - that's what I said and agreed with. I said they don't need adjusting for variations in the weather.

and they don't.

I'm afraid I would have to disagree with you. My experience in 40+ years of driving suggests it can be advantageous at times.
I always let some air out of my tyres when its thick snow and ice around in the winter if I'm driving at sub 40mph . I find it gives me a much safer ride and more positive traction. I live in the country where most minor roads are very poor, rarely gritted and have no pavements or hedges to mark the sides of the roads .I'm sure you wouldn't need to do this in the towns and cities where roads are gritted and well used.

Heres an Oz site recomendation

[FONT=arial rounded mt bold"]944S2 Tyres and Wheels ​

[FONT=arial rounded mt bold"]Unladen Weight (kg)​

[FONT=arial rounded mt bold"]1340​

[FONT=arial rounded mt bold"]Max Power (bhp)​

[FONT=arial rounded mt bold"]211​

[FONT=arial rounded mt bold"]Wheel Type​

[FONT=arial rounded mt bold"]Cast Alloy ​

[FONT=arial rounded mt bold"]Diameter (inches)​

[FONT=arial rounded mt bold"]16​

[FONT=arial rounded mt bold"]Front Rim Width (inches) ​

2021​

[FONT=arial rounded mt bold"]Rear Rim Width (inches)​

24[FONT=arial rounded mt bold"]25​

[FONT=arial rounded mt bold"]Front Tyres​

[FONT=arial rounded mt bold"]205/55 ZR​

[FONT=arial rounded mt bold"]Rear Tyres​

[FONT=arial rounded mt bold"]225/50 ZR​

[FONT=arial rounded mt bold"]Front Tyre Pressure​

[FONT=arial rounded mt bold"]36psi​

[FONT=arial rounded mt bold"]Rear Tyre Pressure​

[FONT=arial rounded mt bold"]44psi​

 

[xenon]

I think we're talking two different perspectives here. The original poster was asking if tyre pressures need changing from summer to winter as a general rule. You're mentioning "thick snow and ice". I would agree that in such circumstances it may help to reduce pressures but I would soon want them back up again later in the day when the snow had gone and I was going to do some motorway travel. I took the OP question to mean "should I generally reduce pressures over the winter months?" and I maintain that you should not.

 

[pauljmcnulty]

Sooooo,

Wouldn't you want more pressure in snow? Not crossing the North Pole type snow, where you want to ride on top, but UK roads snow an inch or so deep where you want to cut through to get grip from the tarmac? The narrower the tyre the better, I'd have thought. [8|]

 

[peanut]

ORIGINAL: pauljmcnulty

Sooooo,

Wouldn't you want more pressure in snow? Not crossing the North Pole type snow, where you want to ride on top, but UK roads snow an inch or so deep where you want to cut through to get grip from the tarmac? The narrower the tyre the better, I'd have thought. [8|]

noooooooooooo [] well yes ... the narrower the tyre the better for snow maybe but we are stuck with the tyre widths we have on 944 which is pretty wide.

I think instead of debating how many inches and how many psi it would be best to say make your decision on prevailing conditions.
If you have 2" of snow on good town roads you'll probably be fine on normal pressures. However 2" of snow on poor country roads that aren't gritted with low traffic flow and are very hilly you'll probably get stuck on normal pressures.

If you ever get stuck in the snow unable to move and you let all the air out of your tyres to about 10-15lbs you'll be amazed at what grip you get. Naturally when the snow goes again or you increase your speed above 25mph you'll need to put the air back ( just put that clearly for xenon's benefit....and black80XSA [][][][])

 

[graham.webb]

The handbook for my S2 coupe says 36 psi all round, and that's all. Haven't all these things got to be subject to the reading accuracy of your tyre gauge? I've found c10% difference between my hand held gauge and the garage. Goodness knows which is correct...

I've found on some cars a small adjustment can improve handling or at least the feel of F/R balance. On the basis that the book allows for inaccurate readings you might decide that anywhere in a range 32 - 40 psi would be worth a try? That seems to have been the range of preference last time this was discussed on the forum.

One thing's for sure, too low and you risk sidewall damage/blowout, too high and the crown of the tyre wears out quicker.

 

[Black80XSA]

Pressures in winter should be no different to summer provided yo are using the same tyres - the recommended pressures are based on retaining the correct flex and stability in the side wall of the tyre. Just remember to check the pressures often, as 4'C drop in temperature leads to a reduction of 1psi.

The use of higher pressures for full load is to retain the side wall profile, reducing an increase in tyre temperature from additional flexing of the carcase (as it would with increased weight and std pressures). Ditto at prolonged high speeds (above UK speed limit) since there may be additional cornering load on the sidewalls at increased speeds. Undeerinflated tyres cause increased side flexing and increased heat build up in the tyre, causing delamination and blow-outs - in wet condition they also lead to increased aquaplaning as the central part of the tyre is not in contact with the road. Overinflated tyres incres the risk of damage and blowouts from impacts such as potholes, and a reduced footprint on the road (running on the centre line of the tyre, not the full width).

Reducing pressures in snow ? - in deep snow it can add traction, but only for low speed manoeuvres.

In snow the best thing you can do is fit narrow tyres - thats why minis and beetles were great in the snow.

 

[peanut]

ORIGINAL: Black80XSA


Reducing pressures in snow ? - in deep snow it can add traction, but only for low speed manoeuvres.

that is what was clearly stated

In snow the best thing you can do is fit narrow tyres - thats why minis and beetles were great in the snow.

are you suggesting we fit narrow tyres on our 8" rims when it snows ?

 

[pauljmcnulty]

ORIGINAL: peanut

ORIGINAL: Black80XSA


Reducing pressures in snow ? - in deep snow it can add traction, but only for low speed manoeuvres.

that is what was clearly stated

In snow the best thing you can do is fit narrow tyres - thats why minis and beetles were great in the snow.

are you suggesting we fit narrow tyres on our 8" rims when it snows ?

[][][]

Maybe we should pick up some of the narrow wheels off all the Golfs and VW busses that are being fitted with our wheels....

 

[Alpine]

ORIGINAL: graham.webb

I've found c10% difference between my hand held gauge and the garage. Goodness knows which is correct...

tyres should always be tested after the car has been stood for a while, not after a drive when the tyres/air will be warm. Testing them at a garage to which you have probably driven will give an inaccurate reading.

 

[peanut]

ORIGINAL: pauljmcnulty

ORIGINAL: peanut

ORIGINAL: Black80XSA


Reducing pressures in snow ? - in deep snow it can add traction, but only for low speed manoeuvres.

that is what was clearly stated

In snow the best thing you can do is fit narrow tyres - thats why minis and beetles were great in the snow.

are you suggesting we fit narrow tyres on our 8" rims when it snows ?

[][][]

Maybe we should pick up some of the narrow wheels off all the Golfs and VW busses that are being fitted with our wheels....

[][][][] did you ever see the youtube footage of the racing vdub camper van beating a 911 and Aston Martin? incredable handling http://www.youtube.com/watch?v=EJM9rQvrkaQ