Pacejka tire coefficients

[orangutan]

This shows an example of what I am talking about, showing a variety of combining techniques. This is a test case where the slip angle is fixed at 1 radian, the velocity is fixed at 10 m/s, and the angular velocity is swept from 0 to 20 rad/s.

This makes it strikingly clear why beckman is more controllable for drifting. A little throttle or brake when highly side loaded does not gobble up side grip suddenly. The transitions are very mild.

Further, I think, this demonstrates quite clearly what is wrong with semi-empirical models for dynamic simulation. Those top three models are probably more accurate for steady state, but when you apply throttle on a real tire, it does not drop side grip off like a cliff on a real tire, because the longitudinal grip has to build up to take it away.