Definition
On an aircraft tire, the bead is the reinforced inner edge of the tire that seats against the wheel rim and holds the tire securely in place. It is built from high-strength steel wires wrapped and bonded into the rubber, providing the rigid anchor that keeps the tire seated under inflation pressure, landing loads, and braking forces. In welding, a bead is the deposit of filler metal laid down along a joint as the weld is made.
Plain English
The bead is the strong inner ring around the edge of a tire that locks it onto the wheel. In welding, it is the line of metal a welder lays down to join two pieces.
Context Anchor
Seen during aircraft tire inspection, tire installation, and wheel maintenance.
Derivation
From Old English 'bead,' originally meaning a small rounded object. The shape of the reinforced tire edge and the rounded line of deposited weld metal both resemble that small, rounded form, which is how the same word came to label both parts.
Why Pilots Care
A damaged or improperly seated bead can cause the tire to lose pressure or separate from the wheel, leading to loss of control during takeoff or landing.
Intuition Check
Bead does not mean a small loose object here. In this context, it means the reinforced edge of the tire that locks against the wheel.
Example Sentence 1
During the tire change, the technician inspected the bead for cuts or distortion before mounting it on the wheel.
Example Sentence 2
After lubrication the bead seated evenly against the rim as the tire was inflated to the correct pressure.