One thing to add is that the physics for tire simulation are are just as complicated, if not more, than all the other physics. And incorrect tire simulations can give you some odd behavior. Very good article though.<p>The Pacejka magic formula was refined to help model the tire interactions with the ground. <a href="http://www.racer.nl/reference/pacejka.htm" rel="nofollow">http://www.racer.nl/reference/pacejka.htm</a>