Technical Term
Offset (ET)
The distance from the hub mounting surface to the center line of the wheel.
Deep Dive
Offset, often marked as "ET" (from the German "Einpresstiefe"), determines how far in or out a wheel sits. A lower offset (e.g., ET20) makes the wheel stick out more (Poke). A higher offset (e.g., ET50) makes it sit further inside the wheel well (Inset). getting this wrong causes rubbing or suspension contact.
Related Concepts
PokeInsetRubbingSpacers