Definition
A wheel alignment condition in which the front edges of the main landing gear wheels are angled slightly closer together than the rear edges, so that if the wheels were rolled forward freely they would converge toward each other.
Plain English
The wheels point slightly inward at the front, like a person standing pigeon-toed. Looking down at the aircraft from above, the front of each tire is a bit closer to the centerline than the back of the tire.
Context Anchor
Seen in aircraft maintenance, landing gear alignment, and tire-wear discussions.
Derivation
From the everyday image of standing with your toes pointed inward. Mechanics borrowed the term because the wheels, viewed from above, mimic that stance.
Why Pilots Care
Correct toe-in reduces tire scrubbing, improves directional stability on takeoff and landing, and prevents uneven wear.
Analogy
It is like standing with your feet turned slightly inward so your toes point toward each other.
Intuition Check
Toe-in does not mean using your toes on the rudder pedals. It describes the angle of the wheels when you look down at the landing gear from above.
Example Sentence 1
The mechanic adjusted the toe-in on the main gear after the pilot reported uneven wear on the inner edges of the tires.
Example Sentence 2
Excessive toe-in caused the airplane to pull left during the takeoff roll until the gear was realigned.