Recommended Tyre Pressures

[Saxosim]

Hi All

I got a new set of Pirelli P Zero Rossos installed today and when I asked the tyre garage what pressure they put in they advised the following:

Fronts - 29 psi - 225 40 R18

Rears - 36 psi -265 35 R18

These pressures seem quite higher to me on the rear tyres, I haven’t got the owners manual with the car to check, please can anyone advise of those pressures are okay?

Thanks 

[mid-life]

seem spot on, exactly what I ran mine at when I had a 986S.

[K.I.T.T.]

2.0 bar front, 2.5 bar rear according to the sticker under the front. The above values in PSI are correct.

[Saxosim]

Excellent thanks both, that’s good, the rears just seemed high 

[Menoporsche]

They have an engine to support  

[Saxosim]

Yes Indeed 

[Bluepork03]

It should have the tyre pressures stated on the back of the petrol flap. At least it does on my '03.

[Saxosim]

Thanks will take a look 

[That986]

13 hours ago, Saxosim said:

Thanks will take a look 

If you have an older S then that sticker might be just below the door striker plate on the drivers side, that's where mine is. 

Also those pressures are spot on but in all honesty i run mine slightly higher on the Pirellis as it "feels" better that way.

[Saxosim]

1 hour ago, That986 said:

If you have an older S then that sticker might be just below the door striker plate on the drivers side, that's where mine is. 

Also those pressures are spot on but in all honesty i run mine slightly higher on the Pirellis as it "feels" better that way.

Thanks, I looked on all the pillars and under the frunk and trunk lid and no stickers, just the one which lists the extras fitted etc.

Thanks for confirming the pressures too i will stick with those 

[Patt]

Think my 986 was fuel cap for pressure.  But yes above is factory pressures for 18's

[Greenman]

Does seem strange when you compare to 981 pressures as these are about the same front and back, surely the weight distribution would be similar to the 986?

[That986]

Just now, Greenman said:

Does seem strange when you compare to 981 pressures as these are about the same front and back, surely the weight distribution would be similar to the 986?

Which is why i run my fronts slightly harder in the 986. Feels a lot sharper and lees tendency to float around. 

[Patt]

Had a similar conversation with Chris at Excel wheels - he thinks the 981 pressures are set low for comfort.

He said other 20" cars are much higher.

[Greenman]

1 minute ago, Patt said:

Had a similar conversation with Chris at Excel wheels - he thinks the 981 pressures are set low for comfort.

He said other 20" cars are much higher.

Point being though that 981 front = 981 back as far as pressure is concerned.    

981 20” gives two sets of values for ‘comfort’ driving 2.1 bar.  For ‘Sport’ driving 2.3 bar.

part of the point of putting wide tyres on is being able to have lower pressures than you would otherwise, if not, you don’t get any addition rubber on the road and little/no extra grip.

[Patt]

yes good point and I would bet a packet of Jaffas with the Ali frunk the 981 is actually lighter on the front than a 986.

Although I was left confused with 18 winters, as to what pressure.  I'm still learning the 981

[Anker BS]

The recommended pressures are deliberately set to introduce understeer for "safety", in reality to protect stupid drivers who can't catch the rear end when it starts to go. A major drawback is that you will have uneven wear on the rears with the center wearing out before the sides. If you track or autocross your car this becomes clear when you monitor your tire temperatures with a tire pyrometer, the centers of the rears get too hot with the factory pressure. I run my car with lower rear pressure on the road to even out the rear wear, and let the pyrometer tell me what pressure to run at when tracking or AXing.

Ideal tire pressure, as determined above, will vary with weather, tire brand and model, rim size, tire aspect ratio, etc.

Bottom line, the sticker pressures are a starting point, not a final or ideal one.

[james_ly]

58 minutes ago, Anker BS said:

The recommended pressures are deliberately set to introduce understeer for "safety", in reality to protect stupid drivers who can't catch the rear end when it starts to go. A major drawback is that you will have uneven wear on the rears with the center wearing out before the sides. If you track or autocross your car this becomes clear when you monitor your tire temperatures with a tire pyrometer, the centers of the rears get too hot with the factory pressure. I run my car with lower rear pressure on the road to even out the rear wear, and let the pyrometer tell me what pressure to run at when tracking or AXing.

Ideal tire pressure, as determined above, will vary with weather, tire brand and model, rim size, tire aspect ratio, etc.

Bottom line, the sticker pressures are a starting point, not a final or ideal one.

So what pressures do you recommend for the road?

[Anker BS]

I run between 34 and 32 in the rears and 29 in front. Just remember that the best pressure varies from tire to tire and with rim size, I am running 255/45 17" Sumitomo HTR ZIII on my rears.

On the road understeering isn't a problem. On the track and on the autocross track it is.

[That986]

14 hours ago, james_ly said:

So what pressures do you recommend for the road?

I have the same tyres as the OP and found the 32 front and 38 rear was perfect. 

[Anker BS]

So here's how I use a tire pyrometer or an infrared thermometer to check tire pressures on the track or autocross course:

Two tools: A piece of chalk and a pyrometer.

Chalk the tires in three places 120 degrees apart. The chalk mark should extend from the tread down to the side wall.

Drive the track, hard. Check the chalk marks. If the chalk has been work off on the tread down to the edge of the side wall you are good. If it has been worn off on the side wall increase the pressure. If it doesn't get near the edge between the treads and the side wall decrease the pressure. Once you have the wear close to the interface you are in the ballpark.

Now start measuring the temperatures at the center and the two sides of the tread after a run. If the temperatures on the two sides are close your camber is right. If it is higher on the outside than the inside you have too little camber. If its the opposite you have too much. If the temperature is higher in the middle of the thread you have too much pressure. If its lower you have too little pressure.

Remember that these are all warm pressures. You have to learn what the cold pressures need to be by letting the tires cool down and then measuring again.

I use the same pressures on the street because that gives you the best contact area. The camber will bee too high for optimal tire wear. The inside  will wear faster than the outside.

You can use the temperature method to find the optimal street pressure. Alternately, you can observe and measure the wear. If the center wears faster than the outsides, lower your pressure. If it wears slower, increase it.

[Southy]

5 hours ago, That986 said:

I have the same tyres as the OP and found the 32 front and 38 rear was perfect. 

I have Goodyear F1's and run exactly the same pressures, the fronts seem to give much more feedback.

[That986]

41 minutes ago, Southy said:

I have Goodyear F1's and run exactly the same pressures, the fronts seem to give much more feedback.

Totally agree, felt too squidgy at 29.

[Saxosim]

7 hours ago, That986 said:

I have the same tyres as the OP and found the 32 front and 38 rear was perfect. 

Thanks will give mine a good drive out on the current pressures but may up them slightly to your pressures if they feel a bit too soft.  I will be on the borders run in April so I am sure they will get a good testing from what @Davidbf1.com and @RBD914 v2 have told me .  I carry a small air compressor in the boot so can always raise them during one of the stops 

[boxster362]

32 front and 38 rear