Wheel Alignment

Definition:

Forward or backward tilt of king pin or
spindle support arm at the top.

Measured in degrees positive or negative.

Influence on Vehicle Handling:

Too little causes high-speed instability and 
poor directional stability such as wandering.

Too much causes hard steering, excessive road shock, and shimmy through the steering wheel.

Influence on Tire Wear:

Usually not a factor in tire wear.

Definition:

Inward or outward tilt of wheel at the top.
Outward is positive, inward is negative.

Measured in degrees positive or negative.

Influence on Vehicle Handling:

Excessive camber (negative or positive) will cause vehicle to pull to the side with greatest variance.

 

Influence on Tire Wear:

Definition:

Amount that front of wheels is closer together than rear of wheels.  For radial tires, toe should be as close to "0" as possible when vehicle is running. 

Measured in inches.

Influence on Vehicle Handling:

May cause vehicle to track improperly and
steering wheel to be off centered.

 

Influence on Tire Wear:

TOE-IN TIRE WEAR

Feather Edge
 Pointed In

TOE-OUT TIRE WEAR

Feather Edge
Pointed Out

Incorrect toe will cause a feather-edge
 wear pattern across the tire tread that
can be felt as you slice your hand 
across the tread.

Definition:

Inward tile of spindle support arm
or king pin at the top.

Directional control angle measured in degrees that spindle support center line
is tilted from true vertical.

Influence on Vehicle Handling:

Non-adjustable angle that, with camber, controls "scrub radius" to minimize
effects of road bumps on steering.

Influence on Tire Wear:

Rapid tire wear can result from mounting new wheels with different offset that may increase scrub radius by moving tire footprint outside projected pivot point. 

Definition:

Amount that front wheels tow out during turns.  Ideal angle reduces tire scrubbing.

Measured in degrees.

 

Influence on Vehicle Handling:

Does not influence vehicle handling qualities.

 

Influence on Tire Wear: