The Golden Question of PhysX wheels

Hi. I do something similar to your project, namely rally by cars. There is a car on 8 wheels. A forward control (4 wheels).
:
[url=http://img13.imageshack.us/my.php?image ... mimage.jpg

LateralStiffnessFactor and LongitudaStiffnessFactor for all wheels:
wheelShapeDesc.lateralTireForceFunction.stiffnessFactor = 100000000.0f;
wheelShapeDesc.longitudalTireForceFunction.stiffnessFactor = 100000000.0f;

PhysX accepts stiffnessFactor = const, stiffnessFactor it is necessary to consider most. Otherwise here that turns out on car turning movements:

[IMG]:
[url=http://img10.imageshack.us/my.php?image ... image2.jpg
[AVI] = 80 Kb
[url=http://webfile.ru/3220841

There is a variant to do through the formula Pacejka, but I can not understand her.

You do not inform by a FRAGMENT OF CODE, how you decide the given problem?

P.S. sorry for my awful English…