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      07-31-2012, 12:50 PM   #4
will.c's Avatar

Drives: E46M
Join Date: Mar 2011
Location: Central Jersey

iTrader: (5)

Not an expert, but I got a few comments that could perhaps be helpful.

First you can try is tire pressure modulation. The optimal tire pressure (bias) really depends on the tire/track conditions. But there are general rule of thumb within a small window. Of course, if you go outside of this window, you will lose traction both ways, e.g. way to high or way too low will deform the tire in a way that you will lose contact patch area, therefore lose grip.

Now in between those extremes, starting from the very low end, I believe you will gain traction as the pressure goes higher, but only up to a certain point. Again the reason is, in this low pressure region, the higher the pressure, the higher the resistance of tire deformation under hard cornering, hence increase in tire contact patch area. (High pressure = high grip)

On the other hand, in the higher pressure region, as the pressure becomes too high, the tires will become too stiff and bounce around the (uneven) track surface. This phenomenon would be similar to how dampers would be adjusted for track conditions; the more irregular the track surface, the softer they need to be so that they don't bounce around everywhere and lose traction. (High pressure = low grip)

To complicate things further, there are good and bad tire deformations. The above mentioned is the bad case. A good deformation is when the tire flattens ever so slightly under load and increases the overall contact patch area. This is another example of high pressure = low grip.

Having said the above to massively confuse you, I believe that the factory recommended tire pressures (32/36 in your case) typically are more optimized for comfort rather than max grip, allowing more deformation than we'd like at the track/autoX. Therefore, as you increase from here, you would most likely gain grip, but again, not going over that threshold.

If I were you, I'd start from 36/36 or maybe even 40/36, and take the first few sessions as trial and error and react according to observations.

If you still find your car pushing, then I'd look into a square setup next.

(Experts, please correct me if I'm wrong.)