Plain English Meaning
When a tire skids on a wet runway, the friction can heat the water under it into steam. The steam softens the rubber and traps a pocket of vapor that lifts the tire off the surface, so the brakes stop working effectively even at low speeds.
Full Definition
A loss of tire-to-runway friction that occurs when a locked or skidding tire generates enough heat to boil the water trapped beneath it, producing steam that softens and reverts the tire rubber to an uncured state. The reverted rubber forms a seal around a small pocket of steam, lifting the tire off the runway and dramatically reducing braking effectiveness, often leaving a distinctive white steam-cleaned streak on the pavement.
Context Anchor
Encountered in , , and braking discussions for wet or .