996 tyre pressure on 18s

[turk1]

I have just had 4 new tyres fitted and had a 4 wheel alignement done but the car still feels unstable and light at the front end at high speed on the motorway, What tyre pressures are you guys running on 18 inch 225/Front 285/Rear? at the moment mine are 36/44.

[6C4GTS]

IME new tyres - especially PS2 feel poor for the first few hundred miles on a 996.
You could try dropping the pressures by a few psi for this period, I did, but get back to 36/44 as the tyres bed in.

[blackburn]

Our 986s always feels vague and 'floaty' on new fronts for a few hundred miles... Tyre pressure sticker inside filler flap?

[turk1]

blackburn said:

Our 986s always feels vague and 'floaty' on new fronts for a few hundred miles... Tyre pressure sticker inside filler flap?

Tyre pressure sticker inside filler cap does say 36/44 i already know this but the car felt the same before the new tyres and geo, I have only done about 150 miles so far on new tyres so i will see how it goes,but still would be intrested to know what pressure others run.at the moment my vw golf feels safer and more stable on the motorway than my porsche does that cant be right.

[Pugley]

I have found a 25Kg bag of sand in the frunk sorts out the light front end, alternatively fill the tank to the brim and drive 2 up

Edited to say that speeds in excess of 70 also create more front down-force and give the steering a more "stuck" feel.

Only half joking!

Edited by Pugley on Sunday 8th January 14:33

[blackburn]

turk1 said:

blackburn said:

Our 986s always feels vague and 'floaty' on new fronts for a few hundred miles... Tyre pressure sticker inside filler flap?

Tyre pressure sticker inside filler cap does say 36/44 i already know this but the car felt the same before the new tyres and geo, I have only done about 150 miles so far on new tyres so i will see how it goes,but still would be intrested to know what pressure others run.at the moment my vw golf feels safer and more stable on the motorway than my porsche does that cant be right.

Sorry, wasn't taking the mickey re the sticker - just wanted you to be aware of it if you'd never noticed it. I can't comment on recommended pressures as a Boxster owner but do ensure the tyres are fully scrubbed in. Our car has had two new sets of fronts during our ownership (different brands) and both felt floaty / vague until fully scrubbed in.

[MrCooke]

I prefer low thirties / high thirties cold. It helps lessen tramlining and makes the ride a little better.

A light nose is more likely to be geo related, but as others have said give it a few hundred miles for the tyres to settle in before you panic.

[sportsandclassic]

Firstly, what tyres have you got fitted? Who has done the wheel alignment ?

[Chris Stott]

I run 32f 38r (2000, 2WD, 18's) on mine as stability, ride and handling all feel much better to me.

[turk1]

sportsandclassic said:

Firstly, what tyres have you got fitted? Who has done the wheel alignment ?

Hi Mike,

The tyres are continental n2 all round, And i had the alignment done by a local company Dixon motor sport who do alot of work on race cars using a hunter machine,Ive got M030 suspention on the car and he set it up with gt3 rs settings as he said it will handle better than standard factory setting with M030.

[MrCooke]

turk1 said:

Hi Mike,

The tyres are continental n2 all round, And i had the alignment done by a local company Dixon motor sport who do alot of work on race cars using a hunter machine,Ive got M030 suspention on the car and he set it up with gt3 rs settings as he said it will handle better than standard factory setting with M030.

Is it running GT3RS ride heights?

[sportsandclassic]

Hi, first of all are you running MO30 or the tequipment suspension kit with roll bars?

I doubt you could even get rs settings on a normal 996. It needs setting up properly. Have you got the printout..? If so can you upload it or type the figures out ?

Tyres will be fine for light track work and fast road.

Mike

[turk1]

MrCooke said:

Is it running GT3RS ride heights?

Hi cooke,

Dont know the answer to that,I think its more a fast road set up but the car does feel better now, my only concern was with motorway speed the car feels a bit floaty, and it felt the same before new tyres and geo, thats why i thought of lowering the tyre pressure a bit.

[turk1]

sportsandclassic said:

Hi, first of all are you running MO30 or the tequipment suspension kit with roll bars?

I doubt you could even get rs settings on a normal 996. It needs setting up properly. Have you got the printout..? If so can you upload it or type the figures out ?

Tyres will be fine for light track work and fast road.

Mike

It has M030 on the sticker under the bonnet,

On the printout it does say GT3:RS (Modified specification)

Current measurements are
Left front camber -0*24 right front camber -0*38
left front caster 7*42 right front caster 7*33
left front toe 0*02 right front toe 0*02


Left rear camber -1*49 right rear camber -1*47
left rear toe 0*14 right rear toe 0*14

[sportsandclassic]

turk1 said:

It has M030 on the sticker under the bonnet,

On the printout it does say GT3:RS (Modified specification)

Current measurements are
Left front camber -0*24 right front camber -0*38
left front caster 7*42 right front caster 7*33
left front toe 0*02 right front toe 0*02


Left rear camber -1*49 right rear camber -1*47
left rear toe 0*14 right rear toe 0*14

Hi, well front end is out as it is different reading side to side and from those figures it will pull to the left and feel very vauge when full of fuel... A gt3 rs camber figure is -0*50 per side. I would of set your car with:

Front camber -0*40 per wheel.
Front toe 0*05 toe in per wheel.
Caster is not adjustable on std suspension. But a gt3 should be 8*30 per wheel.
Rear camber -1*30 per wheel.
Rear toe 0*12 toe in per wheel.

Road tested with customer and report. If still slight floaty front end then get some more toe in on front end.

All done on 1/2 tank of fuel...best of both worlds in my experience.

Obviously a full check over of suspension components before any adjsutments.

Mike

[turk1]

sportsandclassic said:

Hi, well front end is out as it is different reading side to side and from those figures it will pull to the left and feel very vauge when full of fuel... A gt3 rs camber figure is -0*50 per side. I would of set your car with:

Front camber -0*40 per wheel.
Front toe 0*05 toe in per wheel.
Caster is not adjustable on std suspension. But a gt3 should be 8*30 per wheel.
Rear camber -1*30 per wheel.
Rear toe 0*12 toe in per wheel.

Road tested with customer and report. If still slight floaty front end then get some more toe in on front end.

All done on 1/2 tank of fuel...best of both worlds in my experience.

Obviously a full check over of suspension components before any adjsutments.

Mike

Thanks for your advice Mike,the values you suggest are not miles out of what i have on my car and i have not noticed any pulling to the left yet,all the settings were green on the printout so i will see how it goes for now ,if i do notice any pull when i drive it again (which is not very often) i will take it back and get them to reset a the values you suggested.

[MrCooke]

They are actually quite different, a little is a lot! Not saying the firm have done badly of course.
8
You say it was like it before the tyres and geo? If you're new to Porsches it could well be you're mistaking lightness for the directness of the steering on a 911. A 911 changes direction with far less steering input than a Golf and this is exaggerated at speed. A GT3 feels very twitchy at 80mph until you get used to it, most folk used to shopping cars spend the first miles behind the wheel of a 911 over correcting the steering and weaving up the road.

I'd drop the pressures, then get a specialist to go up the road in the car to give you their opinion. It may be nothing or it may well be kippered coffin arms.

[turk1]

MrCooke said:

They are actually quite different, a little is a lot! Not saying the firm have done badly of course.
8
You say it was like it before the tyres and geo? If you're new to Porsches it could well be you're mistaking lightness for the directness of the steering on a 911. A 911 changes direction with far less steering input than a Golf and this is exaggerated at speed. A GT3 feels very twitchy at 80mph until you get used to it, most folk used to shopping cars spend the first miles behind the wheel of a 911 over correcting the steering and weaving up the road.

I'd drop the pressures, then get a specialist to go up the road in the car to give you their opinion. It may be nothing or it may well be kippered coffin arms.

Hi, you could be right maybe i do need to get use to it more, does not help with not driving the car much. The tyres i replaced were 6 years old so i put it down to them been hard tyres but with the new tyres i expected it to be a lot better. If you think my cars geo has been set up wrong i dont mind you telling me so, as i know nothing about geo values.
Mike has already said he would have set the values different as you can see by his post, but i dont know if what i had done by dms is that bad that i should get them to re do the goe again using Mikes settings, unless someone tells me there is a lot of difference or it is a bad set up.

[6C4GTS]

Regular and accurate geo set up is the most important piece of maintenance on these cars - but all too often its the first neglected.

I would get the car set up again - it may not even be at what DMS set it to - one pothole can knock the settings out.

[turk1]

6C4GTS said:

Regular and accurate geo set up is the most important piece of maintenance on these cars - but all too often its the first neglected.

I would get the car set up again - it may not even be at what DMS set it to - one pothole can knock the settings out.

Hi,I only got it done on saturday,But like cooke said maybe i need to get used to the car more. But after what Mike said in his post it's got me thinking are the geo values wrong?