Incorrect toe in/out (tracking) is one of the main reasons for premature tyre wear on vehicles.
The most common sign of incorrect tracking is usually irregular, “feather type” wear across the width of the tread. This is caused by the wheels failing to run in the correct direction and having to be “pulled” back into line as the vehicle travels. This pulling effect leads to the tyre scrubbing on the road surface, resulting in irregular wear and a tendency for the vehicle to pull to one side. It can also have a detrimental effect on vehicle fuel consumption due to the increased rolling resistance of the incorrectly-aligned wheels.
The two diagrams show an exaggerated view of incorrect wheel alignment. The top diagram shows toe-in, which will increase wear to the outer edges of the tyres. The bottom diagram shows a vehicle with excessive toe-out, which will increase wear to the inner edges of the tyres.