Toe is the difference in distance between the front and rear edges of the front tires. Toe helps stabilize steering and minimize tire scuffing by ensuring that the tires roll parallel to each other. Incorrect toe is a common cause of tire wear.
Toe-in means the front of the tires are closer together, toe-out means the front of the tires are spread apart.
In other words, tires that appear pigeon-toed are toed in, tires that look duck-footed are toed out.
Setting static toe-adjusting it with the vehicle stationary-compensates for minute amounts of normal clearance in the steering linkage or steering system. Plus, it compensates for the natural tendency of the front wheels to toe in on a front-drive vehicle and toe out on a rear-drive vehicle.
Once again, toe helps the tires roll as parallel as practically possible when the vehicle's in motion.
Toe is usually specified in inches but may be called out in degrees.
Most manufacturers call for zero to as much as 1/8-inch (0 to 1/8-inch) toe out on front-drive vehicles. Rear-drive vehicles usually have about 1/8-inch toe in.
Individual toe is the toe of each tire compared to the vehicle centerline. Total toe, the sum of each tire's individual toe, is the value shown in wheel alignment specification books.
So, a toe specification of 1/8-inch actually means 1/16-inch at each tire.
When a technician doesn't do wheel alignments often, it's not uncommon for him to confuse total toe with individual wheel toe.
Among the three major alignment angles-camber, caster and toe-toe is always checked and adjusted last.
Too much toe causes severe tire scuffing and may create a sawtooth or feather-edge wear pattern across the tire.
Note that unlike front toe, rear toe causes a telltale diagonal wiping or scalloping effect. For additional details on rear toe and camber, refer to Parts & Labor, Feb. 11, 1991, and March 7, 1994.
Excessive toe out, which causes wander, may be accompanied by a feeling of sloppy, imprecise or unstable steering.
The most common cause of toe-related tire wear is excessive clearance in the steering linkage or steering system. This includes a worn or loose steering box, worn pitman arm, worn steering link or worn tie rods on a traditional steering system.
The technician should always check toe after replacing a steering box or pitman arm because you can't assume the replacement part(s) will be in precisely the same location as the original ones.
On a vehicle with rack-and-pinion steering, a loosely mounted rack assembly, sloppy rack mounting bushings, or worn tie rods create toe trouble. Severe wear on the rack or
pinion teeth themselves could also alter toe.
Always follow the aligner maker's recommendations for adjusting toe so the steering wheel spokes are
``level'' (steering wheel position indicates straight ahead when the
wheels are pointed straight) after the final toe adjustment.