GT3 Mk 2 front camber - different for different tyres?

[Harris_I]

Hi all.

Am intending to swap my Michelin PS2s for a set of Pirelli Corsas.

The front Michelins tend to wear on the outer edge, suggesting my tyre pressure is low. However, I like to run them low for autocross and track days as this tends to dial out a fair amount of understeer and allows for increased tyre temps. Afterwards I pump them back up to a tad less than regulation 32psi cold. (Tracking is confirmed as factory standard).

I guess one solution is to set a couple of degrees negative camber at the front - this will give me the turn-in I'm looking for and reduce the outer wear. Am I right?

Also if I swap to the Corsas, will I need to readjust the tracking? I am likely to swap regularly between the road and track tyres therefore I would strongly prefer not to reset tracking every time.

[johnfm]

Harris_I said:

Hi all. Am intending to swap my Michelin PS2s for a set of Pirelli Corsas. The front Michelins tend to wear on the outer edge, suggesting my tyre pressure is low. However, I like to run them low for autocross and track days as this tends to dial out a fair amount of understeer and allows for increased tyre temps. Afterwards I pump them back up to a tad less than regulation 32psi cold. (Tracking is confirmed as factory standard). I guess one solution is to set a couple of degrees negative camber at the front - this will give me the turn-in I'm looking for and reduce the outer wear. Am I right? Also if I swap to the Corsas, will I need to readjust the tracking? I am likely to swap regularly between the road and track tyres therefore I would strongly prefer not to reset tracking every time.

Low tyre pressure should wear inner and outer edge.

[Harris_I]

Yep, I am aware of this. My question is really: given that under standard factory geometry, the Mk2 is set up for initial understeer, and one has to reduce pressures considerably for track work, would a hint of negative camber at the front not only give me the turn-in I need, but also inherently avoid the need to drop pressures by quite so much and maintain reasonably even wear across the fronts?

Secondly, would I need to adjust tracking every time I swap tyres PS2<->Corsas?

Thanks for any advice.

[Glenn McMenamin]

Harris_I said:

Yep, I am aware of this. My question is really: given that under standard factory geometry, the Mk2 is set up for initial understeer, and one has to reduce pressures considerably for track work, would a hint of negative camber at the front not only give me the turn-in I need, but also inherently avoid the need to drop pressures by quite so much and maintain reasonably even wear across the fronts? Secondly, would I need to adjust tracking every time I swap tyres PS2<->Corsas? Thanks for any advice.

I don't think there is much middle ground here.

Running more negative on the front will certainly give you the turn in you need, but whatever you do, make sure you do the rear aswell, otherwise your ass will be hanging out everywhere.

With regard to tyre wear, with negative camber running, you will get much more even tyre wear on track days, as the car rolls onto the flat of the tyre, however, if you do mainly road miles, you will start to see the inner edges of the tyre wear out far quicker.

I believe that certain tyres are best at different degrees on the car, i think this is due to sidewall strenght, but not sure.

I don't think you will have too much of a problem if you change from tyre to tyre, you just need to decide which optimum setting to stay with, road tyre, or track tyre.

Hope this helps.

G.

[Harris_I]

Thanks Glenn - that's helpful. BTW, I may opt for Cups instead as I just found out our local Michelin rep who has worked on Porsche track set-ups should be able to advise me an appropriate geometry for both PS2 and Cups.

>> Edited by Harris_I on Tuesday 30th August 09:44

[big.bad.wolfie]

If I understood Silverline correctly when they fitted Corsas to my C4S, the Corsa has more tread towards the inner edge, almost as if the tyre is planed at a angle so it is specifically designed to work with higher than norm negative camber settings.

Damian