Air Pressures and Handling - 996 Carrera 4

[PorscheFreak]

Chaps,

I checked the pressures on my Carrera 4's tyres a couple of days ago, they were all at around the 30psi mark.

I have the 18" Turbo alloys with the staggered rears at 265.

Under the hood the factory guide was something like 36psi for the fronts, and 44psi for the rears!

I pumped them up to the guidlines and now the handling feels a bit skittish in the wet, not something I could ever accuse the 4 of being before.

I've noticed fairly obvious understeer going into a few roundabouts a bit hot (wet tarmac) and also had to correct the rear a couple of times coming out of roundabouts (wet tarmac) no biggie to do, but never really had this before.

Should I just back off the pressures a little and take the worse fuel consumption but grippier handling. Or does running with a lower pressure not actually give you additional grip? I genuinely don't know.

For reference the tyres are P-Zero Rosso's all round.

Cheers

[Rockster]

The inflation pressures you found may be for a fully loaded car. My 03 Turbo has similar numbers and the techs tell me the pressures are for a fully loaded car. Consequently the car comes out of the service bay with lower f/r tire pressures. Lower by just several psi.

To run 30psi all around is I believe -- but have no reference to back this up -- way too low.

You might try 2psi lower than the 36/44 numbers and see how that feels. If you want drop the cold pressure by another 2psi to say 34/42 and see how that feels.

Whether you can go any lower I can't say. Not sure where you can find out how low you can go and still have the tires properly inflated.

[Zoin]

My 996 C2 on 18s has the same 36/44 recommendation and like you, I found the handling a bit skittish. I checked a few forum threads and found many people use lower pressures. I guess it's a case of trial and error to find what works best for you and your car but I've been using 32/36 for the last 2 years. Tyre wear is even across the tyre.
Since yours is 4wd and so presumably heavier at the back, you might be better off with 38 or even 40. Just a guess.

[damiangt3]

That 36/44 is for something like an old Michelin Pilot Sport 1, they needed that to cope with the thin side walls.

[Zoin]

damiangt3 said:

That 36/44 is for something like an old Michelin Pilot Sport 1, they needed that to cope with the thin side walls.

Interesting. I'm using Michelin PS2s. Do you know if they have thin sidewalls too?

[damiangt3]

Zoin said:

Interesting. I'm using Michelin PS2s. Do you know if they have thin sidewalls too?

No, they are far thicker.

[Zoin]

damiangt3 said:

No, they are far thicker.

Thanks for that info Damian - I was starting to worry about using low tyre pressures!