This is what you can learn (it does apply to 1/8th):
Physical Forces and Setup - Theory and Practice_by James Hughes
The steering geometry can be regarded at the movement and displacement of the front wheels as the steering wheel is turned. This movement is quite complex, and involves a number of different settings. There is one thing in common though, and that is the reason why we need a complicated geometry - We MUST lift the inside wheel while cornering.
The inside wheel lift is what enables a kart to go round a corner without using a differential.
Because of this lack of a differential, a karts natural direction of travel, forwards, is very difficult to change. This is down to the differing radii of turn experienced by the inner and outer rear wheels while turning a corner. The inside wheel is actually travelling a shorter distance than the outside, so therefor is needs to take fewer revolutions to go round the corner. However, the two rear wheels are attached by a solid axle, and must therefor move together, so in order to turn, one of the wheels need to skid over the track surface. In a car, the differential will allow the wheels to turn at different rates, without this skidding action.
This skidding action, or indeed the lack of it, is what make a stationary kart so difficult to turn round - you have to overcome the grip of one of the tyres, and with the sticky tyres used in many kart classes this can expend a lot of energy.
This is the reason for lifting the inside wheel and it effectively turns the kart into a tricycle during the cornering process! The steering geometry causes the inner rear wheel to lift off the ground while cornering, which means the wheel can rotate faster than it is passing over the ground. The rear inner wheel is no longer touching the track, and we therefor no longer need to overcome the grip from that tyre in order to turn.
In fact, depending on the power of the engine, we may be able to allow some scrub. For example, while a Prokart may need to entirely lift the inner wheel, because it does not have enough power to overcome the scrub, a more powerful kart may have power to spare in the corner, meaning that the power loss to scrub can be overcome. However, any scrub will start to cause understeer when entering a corner, so even though the engine may be powerful, it may still be necessary to completely lift the inner rear to maintain decent handling."