What PSI?

[eoin27]

Hi all. i was wondering what PSI should I use for the car?

Right now its on 32 psi but i'm not too happy with the grip and its a bit "bouncy" over bumps.

I dont want it too low either which would hamper performance and fuel economy

They are the excecutive 15" alloys given out on the D9's

Also - purchased a OBD II tool on ebay for my laptop to car. Also bought a few DVD's with a load of diagnostic software. Has anyone had a go at remapping themselves? If so, some tips would be nice. Dont want to ruin the car

[mjb]

On my turbo exec estate, I ran 35 at the front and 39 at the back for improved fuel economy against the specified 34 front, 35 rear.

Haven't checked the tyres on my V6 yet, but I'm thinking about whatever's specified at the front and a few psi more at the back. More front wheel grip, less rear grip ( ) and an economy boost.

I suspect with as low as 32psi in, your tyres aren't doing much in the middle, which'll hurt grip especially if you've got one of the heavier engines. Check the plate in the driver's door panel for the recommended pressure.

[eoin27]

I must do that. I didnt know there was a psi plate in the drivers door. I'm running on firestones and i havent seen anything about psi on the tyre walls

[steve_earwig]

Umm, that'll just be the maximum and you don't really want to do that.

Are you sure your pressure gauge is accurate? I have 4 and they all read slightly different...

[mbell666]

the plat on the door will probably be in bar (french ). I think its something like 2.25/2.3 i normally run mine at 2.35/2.4 which is something just under 35 psi in real terms.

[steve_earwig]

...will probably be in bar (french ).

Bollocks, English.

The bar and millibar were introduced by Sir Napier Shaw in 1909 and internationally adopted in 1929.

If it was French it'd be in kilopascals.

[mjb]

The plate on D8s has both PSI and bar. Chances are the D9 one will be the same

[eoin27]

checked the plate on the inside of the door. It says 2.3 bar, its not in psi. Converted to psi it is somewhere in the region of 33.5.

Theres a picture of a big bucket inside a car and another of a small bucket inside the car on the plate. I'm assuming this is for big and small loads. Anyway the measurement given is 2.3 bar in both instances.

[DaiRees]

Aye, on the estate it's 2.3 front and 2.4 rear IIRC (I run them at 33 and 35psi), except for when fully loaded then the rear goes up to 3.2 bar, which is 46 psi

[mjb]

Aye, on the estate it's 2.3 front and 2.4 rear IIRC (I run them at 33 and 35psi), except for when fully loaded then the rear goes up to 3.2 bar, which is 46 psi

Haha yeah I remember on my way to Germany last year with a FULL estate. Stopped off at a garage for fuel and air, and had a right nervous time pumping that much air in the back - I was half convinced I'd end up with a chunk of exploded rubber blown through my abdomen!