Model it........... The side force acting on the tire contact point if you are turning to the left will be to the right...... steering out of the turn. Look at a bicycle........... The straighter the forks the snakier the steering. The more rake (bend forward), the more directionally stable. I have one bike you can ride hands off all day long....... another you virtually can't take your hands off at all. Note also that all automotive steering kingpins lean back at the top (positive caster), and the more they lean back, the more directionally stable they are. I've built rear steer vehicles......Reversed trucks with loaders mounted on them, and I can tell you that you have to flip the steering axle around to it's normal orientation when you reverse the machine or you will be chasing it all over the place. Look at the way your tires lean in a turn, and this is obvious without even crawling under to look. The more you tilt your steering axle .... positive caster.... the more the contact patch moves forward relative to the steering axle......... and the more stable it becomes........ front or rear steering.
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Originally Posted by Christ
How would the contact behind the kingpin cause it to want to turn further in?
Casters work on this principle already... they always move to center when trailing...
Move the kingpin behind the contact patch of the tire, and it doesn't matter what (reasonable) caster angle you have, the forward momentum is going to cause oversteer as the road friction tries to push the tire further off center, instead of further toward center.
Edited to clarify -
I know that Macpherson strut and any other kinds of steering/suspension use the system that you're talking about, but those systems also use an offset steering angle with positive force on one tire helping the return, due to there being two tires, one always going slightly faster than the other in turns.
Now we've got one tire, trailing a single line on the surface. Don't think it's gonna work out the same way.
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