Definition
A wheel alignment condition in which the front edges of the main landing gear wheels are angled slightly outward, away from each other, so that the distance between the front of the tires is greater than the distance between the rear of the tires when viewed from above.
Plain English
The two main wheels are set so they point a little bit outward at the front, like the tips of your toes spreading apart while your heels stay closer together.
Context Anchor
Seen in landing gear maintenance, tire-wear discussions, and preflight concerns about wheels that do not appear to track straight.
Derivation
The term is borrowed directly from automotive and mechanical usage. 'Toe' refers to the front of the wheel (as the front of a foot), and 'out' indicates the direction it points. Picturing your own feet with the toes turned outward gives the exact geometry.
Why Pilots Care
Incorrect toe-out produces uneven tire wear, ground handling instability, and increased risk of nose-wheel shimmy during takeoff and landing rolls.
Analogy
If your feet are pointed outward while you walk, they are toe-out. Aircraft wheels can be aligned in a similar outward-pointing way.
Intuition Check
Toe-out does not refer to toe brakes or how the pilot’s feet are placed on the pedals. It refers to the alignment angle of the aircraft wheels.
Example Sentence 1
The mechanic measured the main gear and found a slight toe-out condition that was causing the tires to wear on their inner edges.
Example Sentence 2
Excessive toe-out on the main gear caused rapid wear on the outer tire shoulders.