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Tyre pressures adjusted. Holy Christmas what a difference!

I have always enjoyed harder tyres than recommended, until I got my 996. After loads of experimentation I do 34 / 36 on my car. I think 44 is shockingly hard and costs you loads of grip, especially in the winter!!
 
'These tyre filling pressures apply only to the tire makes and types approved by Porsche.'

I.e. If you are not running n-rated tyres different pressures may be applicable..
 
asterix_the_gaul said:
'These tyre filling pressures apply only to the tire makes and types approved by Porsche.'

I.e. If you are not running n-rated tyres different pressures may be applicable..

Slightly different point, but do agree with others on this site that the whole N-thing is garbage - a 'system' whereby manufacturers pay Porsche for them to 'test' their tyres and then 'specify' them. Seems very like 'cash for access to the market'.

But I do agree that tyres pressures could vary - depending on the roads, type of use, weather, temperature, etc. People who have never been involved in the racing scene will probably be surprised to realise that racing tyres are pumped as low as possible/permissable - for maximum grip.
 
And the fact they get seriously hot and therefore increases the pressure dramatically whilst on the track!
 
crash7 said:
32/34 hot - Yoko recommend not going above 34 with AD08R.

You use Yoko AD08Rs on your Porsche? How do you find them in comparison to, say, Michelin Pilot Sports?

I have the AD08Rs on the Lotus, absolutely love them and was wondering if I could go that way with the Porsche as well!
 
After some early experimentation, over the last 4000 miles I've been using 34f/40r on my non N rated Michelin PS4 tyres (225/40x18 and 275/35x18 as they don't make a 285/30 rear), the grip is fantastic even down to 2c on a drive out last Saturday morning and definitely nothing like a waterbed.

My car has M030 suspension and a fast road geo from CG following a refresh of anything that was a bit worn and tyre wear is very even across all treads.
 
'Big Joe' JCX is the expert on here for tyre pressures :thumb:
 
As touched on by others pressures are subjective with there being many variables.

Porsche numbers are recommendations based on a multitude of factors that the factory need to meet, fuel efficiency/mpg as an example. - They also need to ensure that every environment the car will be sold or driven in is catered for they are not, for example, UK B-Road specific.

Similar to an engine map, it's not for a particular environment, more of a jack of all trades, taking into account many variables.

Michelin recommend 33/36 hot on the Cup2 for the 991 GT3, this is a focused car with performance in mind, as oppose to the Carrera jack of all trade numbers.

Hot numbers are also more relevant, as if your driving in the winter in the UK or on track in Florida, hot is hot and you set accordingly.

Cold numbers are ball park at best, 44 cold in a cold environment would stay at 44, 44 cold in a warm environment would rise circa 3-4 psi, which does not sound much buts its circa 10%. – Yet the Porsche recommendations are the same for both, optimal, I think not.

Pressures are also dependant on the tyre you use, what you want from it, how you want the car to feel, suspension setup, car weight and your driving type & style, if your sitting at 80mph all day long on the motorway a higher pressure would be ok, you don't need grip driving in a straight line, higher pressures also manage wear better.

Personally I want grip and am not interested in wear or mpg economy, I run around 32/34 - 33/36 hot on Yokohama AD08R, if they get over 39 I find they become greasy and grip less. - On track to attain 32/34 I need to be running around 4-5 psi lower when cold, circa 28/30.

Most change parts on their cars to try and improve performance, tune the setup to their environment, exhausts, suspension etc etc, tyre pressures are no different, if your prepared to change other parts that are not Porsche why not tyre pressures.

In my eyes there is no right or wrong do what feels good for you, don't be afraid to experiment based on the comments of others, particularly when they do not have all the information or know what your looking for, in this instance there is also little work and no cost involved, trial & error!
 
DerbyJim said:
crash7 said:
32/34 hot - Yoko recommend not going above 34 with AD08R.

You use Yoko AD08Rs on your Porsche? How do you find them in comparison to, say, Michelin Pilot Sports?

I have the AD08Rs on the Lotus, absolutely love them and was wondering if I could go that way with the Porsche as well!

I find them excellent with performance closer to Michelin Cups than Pilot Sports, dry grip is perhaps just short of what you see from Cups, but wet grip is better.

When all things are considered, wet & dry grip, predictability, cost I think you will struggle to find a better all round duel purpose (Road & Track) tyre.
 
crash7 said:
DerbyJim said:
crash7 said:
32/34 hot - Yoko recommend not going above 34 with AD08R.

You use Yoko AD08Rs on your Porsche? How do you find them in comparison to, say, Michelin Pilot Sports?

I have the AD08Rs on the Lotus, absolutely love them and was wondering if I could go that way with the Porsche as well!

I find them excellent with performance closer to Michelin Cups than Pilot Sports, dry grip is perhaps just short of what you see from Cups, but wet grip is better.

When all things are considered, wet & dry grip, predictability, cost I think you will struggle to find a better all round duel purpose (Road & Track) tyre.

Thanks, I echo your sentiments here and your post above.

I don't track the Porsche (and have no desire too either) but was wondering how the tyre performed on a heavier car. Sounds similar to my experience in the Lotus - good balance on wet and dry, probably my preferred choice unless you want to spend double the money and then you're looking at either wet OR dry rather than a decent balance between the both e.g. AO48 tyres will cost me nearer 1k rather than a set of AD08Rs for £440 all round.

Changing / monitoring tyre pressures to suit the heat in the tyres is one thing I have learnt from doing many trackdays in the Lotus over the last 2 years. It makes an unbelievable difference and one that you don't really notice in day to day driving.

The AD08Rs also get heat into them reasonably quickly.

Might have to check them out for the Porker next time it needs them!
:thumb:
 
Demort said:
Tyre pressures should be set from memory at 20 degrees tyre temp .. so to be spot on a road test then adjust them .

I would agree with say 3 psi lower but more than that and i feel , although i could well be wrong , that you will get uneven tyre wear .. that would be rather expensive .

I can say from experience that low tyre pressures can make a car feel anything from excellent to unstable .. i guess there is a sweet spot but either way then close to the original pressures is what i would have to recomend .

I work in bar so depending on what wheels / tyres you have fitted it should be either 2.5 bar or 2.5 front and 3.0 rear , your original setting would seem to be wrong and a geo should be done with correct tyre pressures .. its kinda basics 1 O 1 on a geo adjust to have correct pressures .

No offence young man.. id hate to cause that .

We basically run 2.5/3.0 depending on the tyre pressure as well. But it has to be set at 20c e.g. when the tyre is cold. The problem is that it doesn't take much driving for them to creep up above 20c.

You are not suppose to run less than 0.5 bar below those.

Then you have the difference between half load and full load and so on.

If you car is sitting outside overnight in these temps then for each 10c less you should expect the tyre to be 0.1 down.

And don't rely upon garage forecourt tyre gauges - they vary too much. Our gauges are calibrated each year but we check regularly each gauge against the others to ensure they are fine in between.

Other factors such as tyre condition and age are going to affect how the car feels as well as outside temps.

Ken
 
This whole question hinges very much on what tyres you have. If you have Cups on a GT3 the recommended pressures are way down at approx 28f/31r (few OPCs actually know this and you should always check that they haven't overinflated them if they have changed your rubber. But they must be Cups to go that low). However, if you are on something like a PS2 or winter tyres then you ought to be up at about 31f/38r. More modern high performance (non-track) road rubber ought to have stiff enough sidewalls for about 29f/36r, but you will have to try it and see once you are below recommended numbers (make sure that you don't have them so low that they roll over the sidewalls).

But no - unless you know people small enough to fit in the back and are driving 4 adults up : you don't want those 40+psi recommended pressures.
 
pg_262_chart_1.jpg


Interesting table, that. It shows that you can change the pressures a hell of a lot, depending on load (and who runs a 911 "full load" - what's the definition anyway?).

36/44 is the same as a 996.2 on 18s, so I wonder if 31/39 would be okay on a '"part-loaded" 996.2 ?
 
I had two rear OEM Michelin's fitted in December on my 996 by the Porsche main agent. They set the pressure on the rears to 36. On the official Porsche website there is a clip on YouTube (a questions & answers session for the 996) this very question is asked. The Porsche mechanic stated that they have found no adverse effects when reducing the tyre pressure on the rears. The original PSI spec of 44 is very high for any road tyre. I have found 36 ish gives a more compliant ride, on public roads. If you are going on track you should be adjusting the pressure anyway.
 
996ttalot said:
Demort said:
We basically run 2.5/3.0 depending on the tyre pressure as well. But it has to be set at 20c e.g. when the tyre is cold. The problem is that it doesn't take much driving for them to creep up above 20c.

You are not suppose to run less than 0.5 bar below those.

Then you have the difference between half load and full load and so on.

If you car is sitting outside overnight in these temps then for each 10c less you should expect the tyre to be 0.1 down.

And don't rely upon garage forecourt tyre gauges - they vary too much. Our gauges are calibrated each year but we check regularly each gauge against the others to ensure they are fine in between.

Other factors such as tyre condition and age are going to affect how the car feels as well as outside temps.

Ken

0.5 bar is 7 psi, which taken off 36/44 is.....29/37. Given the part-load rating on the previous table is 31/39, I reckon 30/38 is spot-on for my car (which I only really ever drive in alone)!
 

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