Porsche 981 Boxtser / Cayman 20" tyre choices - P Zero N1s

[PhantomPH]

I see Pirelli have launched a 'colour' edition which I thought would be very cool to go for red to set off the red contrast elements of my CGTS. £2k for a set??? Hell no!

[hixster]

JayK12 said:

hixster said:

eggy41 said:

Picked the car up tonight from ATS, new Goodyears all round ... short drive home but I can feel the difference in ride comfort already, night and day .... one question ... they're inflated them to 33, I was running the Pirelli's at 31 which I thought was the recommendation

33 front and back on 20"

Starting at 33 is too high in my opinion, as the tyres get warm hot pressures will be way past 33 psi. I found this to be the optimum

As these pressures are printed in the manual, logic would dictate that Porsche would probably have factored in the pressure rising due to heat and provided pressure settings at cold - 33 is the guide for what you have most control over, putting air in the tyres at the pump and not having to anticipate pressure rises due to heat.

pressure can also go down as well so 33 is likely to be a sensible median.

[JayK12]

hixster said:

JayK12 said:

hixster said:

eggy41 said:

Picked the car up tonight from ATS, new Goodyears all round ... short drive home but I can feel the difference in ride comfort already, night and day .... one question ... they're inflated them to 33, I was running the Pirelli's at 31 which I thought was the recommendation

33 front and back on 20"

Starting at 33 is too high in my opinion, as the tyres get warm hot pressures will be way past 33 psi. I found this to be the optimum

As these pressures are printed in the manual, logic would dictate that Porsche would probably have factored in the pressure rising due to heat and provided pressure settings at cold - 33 is the guide for what you have most control over, putting air in the tyres at the pump and not having to anticipate pressure rises due to heat.

pressure can also go down as well so 33 is likely to be a sensible median.

It indicates 33 PSI as the optimum no? I have 2 on my car, one pressure for low speed and another pressure (33) for high speed. As said i interpret this as optimum pressures. If i start at 33 PSI and drive hard in the summer i will end up at 37/38 PSI, which will mean the tyre is over inflated, less tread contact on the road. In the summer I run less so the optimum when driving is 33 PSI, and in the winter run more so the optimum is still 33.

[hixster]

JayK12 said:

hixster said:

JayK12 said:

hixster said:

eggy41 said:

Picked the car up tonight from ATS, new Goodyears all round ... short drive home but I can feel the difference in ride comfort already, night and day .... one question ... they're inflated them to 33, I was running the Pirelli's at 31 which I thought was the recommendation

33 front and back on 20"

Starting at 33 is too high in my opinion, as the tyres get warm hot pressures will be way past 33 psi. I found this to be the optimum

As these pressures are printed in the manual, logic would dictate that Porsche would probably have factored in the pressure rising due to heat and provided pressure settings at cold - 33 is the guide for what you have most control over, putting air in the tyres at the pump and not having to anticipate pressure rises due to heat.

pressure can also go down as well so 33 is likely to be a sensible median.

It indicates 33 PSI as the optimum no? I have 2 on my car, one pressure for low speed and another pressure (33) for high speed. As said i interpret this as optimum pressures. If i start at 33 PSI and drive hard in the summer i will end up at 37/38 PSI, which will mean the tyre is over inflated, less tread contact on the road. In the summer I run less so the optimum when driving is 33 PSI, and in the winter run more so the optimum is still 33.

No, quite the opposite - optimal isn't mentioned - specific temperature is, 33psi is recommend for cold tyres / ambient temperature 20deg - so no need to anticipate temp rise when in use.

[DJMC]

hixster said:

No, quite the opposite - optimal isn't mentioned - specific temperature is, 33psi is recommend for cold tyres / ambient temperature 20deg - so no need to anticipate temp rise when in use.

Correct. I'm sure every manufacturer specifies pressure when tyres are "cold".

[ATM]

DJMC said:

hixster said:

No, quite the opposite - optimal isn't mentioned - specific temperature is, 33psi is recommend for cold tyres / ambient temperature 20deg - so no need to anticipate temp rise when in use.

Correct. I'm sure every manufacturer specifies pressure when tyres are "cold".

They do but as with anything car setup related it is not hard and fast it is just a recommendation and the health and safety heroes get involved so the specified pressure might be a mix of safe and optimum in terms of dynamics. The fact that they tell us in the UK that the comfort pressures are for speeds of less that whatever the number is which none of us will ever do tells us a lot about the way in which these are derived.

[DJMC]

ATM said:

They do but as with anything car setup related it is not hard and fast it is just a recommendation and the health and safety heroes get involved so the specified pressure might be a mix of safe and optimum in terms of dynamics. The fact that they tell us in the UK that the comfort pressures are for speeds of less that whatever the number is which none of us will ever do tells us a lot about the way in which these are derived.

My 981 is pre-TPM. I wonder if there's anything in the manual about "Comfort" settings? I'll have a look some time.
I'm on GY F1 20's with PASM so it's not really been an issue as this feels comfortable to me when in Normal PASM.

[bcr5784]

DJMC said:

My 981 is pre-TPM. I wonder if there's anything in the manual about "Comfort" settings? I'll have a look some time.
I'm on GY F1 20's with PASM so it's not really been an issue as this feels comfortable to me when in Normal PASM.

Why haven't you looked so far? I think you will find it does.

I know complex phones come without any meaningful instructions (and it irritates the hell out of me - why should I pay £4/5/600 for something that I won't be able to fully use without trawling the internet?)

There is no chance that anyone will be able to get full value out of their Porsche unless they read the bloody instructions!

[DJMC]

bcr5784 said:

Why haven't you looked so far? I think you will find it does.

I know complex phones come without any meaningful instructions (and it irritates the hell out of me - why should I pay £4/5/600 for something that I won't be able to fully use without trawling the internet?)

There is no chance that anyone will be able to get full value out of their Porsche unless they read the bloody instructions!

I haven't looked because this is the first I've heard of it, suggesting it's not in the manual which, of course, I read from cover to cover, like your good self, before ever driving the car.

I tend only to look things up if there's a problem. But there hasn't been in this regard.

[bcr5784]

DJMC said:

I haven't looked because this is the first I've heard of it, suggesting it's not in the manual which, of course, I read from cover to cover, like your good self, before ever driving the car.

I tend only to look things up if there's a problem. But there hasn't been in this regard.

Page 232 - there's a whole page on it.

[JayK12]

My tyres hit 2.5 bar this weekend just over 36psi. The edges of the tread went blue which indicates they are too hot / too high pressure. I'm taking all the nitrogen out and replacing with standard air but my fill to 1.9 bar cold for summer.

Looking forward to trying PS4 or Cup2s.

[hixster]

JayK12 said:

My tyres hit 2.5 bar this weekend just over 36psi. The edges of the tread went blue which indicates they are too hot / too high pressure. I'm taking all the nitrogen out and replacing with standard air but my fill to 1.9 bar cold for summer.

Looking forward to trying PS4 or Cup2s.

Your TPM warning light would have come on if they were over pressure.

What does your fill info say at 1.9 Bar? that's almost 20% under inflated / pressure?

I'm not sure why despite the manufacturers recommended tyre pressures, the cars own tyre pressure management system and the hundreds of thousands of test miles Porsche do testing their N rated tyres you would be under inflating them.

"Under inflated tyres means that your vehicle’s rolling resistance will increase making your vehicle more fuel thirsty.

You also increase the likelihood of sustaining a puncture which means even more expense. But most important of all, under inflated tyres reduce your vehicle control, increase braking distances and increase your risk of skidding."** AA

Edited by hixster on Tuesday 4th July 08:57

[JayK12]

hixster said:

JayK12 said:

My tyres hit 2.5 bar this weekend just over 36psi. The edges of the tread went blue which indicates they are too hot / too high pressure. I'm taking all the nitrogen out and replacing with standard air but my fill to 1.9 bar cold for summer.

Looking forward to trying PS4 or Cup2s.

Your TPM warning light would have come on if they were over pressure.

What does your fill info say at 1.9 Bar? that's almost 20% under inflated / pressure?

I'm not sure why despite the manufacturers recommended tyre pressures, the cars own tyre pressure management system and the hundreds of thousands of test miles Porsche do testing their N rated tyres you would be under inflating them.

"Under inflated tyres means that your vehicle’s rolling resistance will increase making your vehicle more fuel thirsty.

You also increase the likelihood of sustaining a puncture which means even more expense. But most important of all, under inflated tyres reduce your vehicle control, increase braking distances and increase your risk of skidding."** AA

Edited by hixster on Tuesday 4th July 08:57

Yup 1.9 bar cold. Once Warm they get upto 2.1 very quickly, and when i get them hot they are at 2.3. This is actually how it came from Porsche when i bought it. Just trying Nitrogen fked it all up.

However if i can find a race car prep shop i can get "real deal" nitrogen and just have it 2.3 all the time, hot cold no difference.

[7184c]

One of my tyres had dropped down to 1.9 bar so before a trip out yesterday inflated with the others which are normally around 2.0/2.1 up to 2.3 cold.

My experience (and even my wife who has zero interest in cars commented and agreed) was that on the higher standard pressure rather than comfort setting the ride was much better. The car is on 20in carerra classics with eagle F1s and PASM.

It may be different without PASM but I won't be bothering with comfort pressure in future.