This is taken verbatim from a mob called Intrax Suspension Technology, and gives a pretty fair description.
If anyone can be bothered to look at it here: http://en.intraxracing.nl/techniek/camber,-caster,-toe-intoe-out/ it also explains about camber and castor as well.
TOE-IN / TOE-OUT
Affects 3 major areas; Tire wear, straight-line stability and corner entry handling.
For minimum tire-wear it would be ideal to have the wheels parralel / 0 degrees while riding.
This can be acomplished to give a bit static toe-out to a frontwheel-drive car, or toe-in to a rearwheel-driver.
A frontwheel-drive car has the tendency to understeer.
Toe-out will induce a bit of oversteer, so it could compensate the frontwheel-driver's understeer.
Excessive toe-in will cause the tire to scrub on the outboards and so will shorten the tire-life.
Too much toe-out will cause the inboard edges to wear out.
Steering response will be improved with toe-out.
Straight line stability will be improved with toe-in.
Sometimes toe-in or toe-out is used for another effect; Tire-temperature.
For racing-tires it's very important to reach a certain temperature in order to deliver maximum performance/gripp.
If the tires stay too cool than toe can be used for the "scrubbing" efect,
The scrubbing also has another positive effect; It will scrub the tires clean providing extra gripp for braking and cornering.
Street cars often are set up with toe-in; For good straight-line stability cornering is sacrefied.
Race cars are often set up with toe-out; Straight-line stability is sacrisfied for good cornering.
If the suspension is independent; Toe-in or -out can also be applied to the rear-wheels. The effect on the rear-wheels is generaly the same as on the front.
Also there's a difference between static and dynamic toe. Especially on a frontwheel-driver you see this happening.
The same goes for a rearwheel-driver with independent suspension left and rear.
What happens is that when torque is applied ; The driven wheels pull themselves forward trying to toe-in.
Now it depents on the construction of the suspension how much the toe-in will increase.
On streetcars this effect is a lot bigger than on race cars as they use softer rubber bushings in the suspension-joints.
These provide more comfort and "kill" more noise but doing so sacrefice precision and stiffness.
CONCLUSION:
All the above is of great importance on the handeling of the car. as well as the level of satisfaction of the driver.
So if possible use factory settings or settings who have proven to be good, as a starting point for a new setup with new springs, shocks, and/or camber-plates on your car.
Investing a vast amount of money in new shocks and not lining the wheels again in a proffesional workshop, could make your suspension-investment absolete!
It could be that you do not feel any improvement of the suspension upgrade. Also your car can easily become unsafe on a straigth, during cornering and/or under braking.
Also we hope you understand more about the lining of a car and at the same time are aware of the importance of it.
