What is Tucked?
Wheel fitment where the tire sits inside the fender line, so the fender lip covers the top edge of the wheel.
Tucked describes a wheel that sits inside the fender line. Look at the car from the side at eye level and the fender lip hangs out past the outer face of the wheel, covering its top edge. It is the opposite of poke, where the wheel sticks out past the bodywork.
Tuck is measured the same way any fitment is: wheel width, offset, tire size, and ride height together decide where the wheel face lands relative to the fender. A higher (more positive) offset pulls the wheel inboard. A narrower tire on the same wheel does the same thing. Dropping the car adds tuck too, because the fender arch curves outward as it comes down over the tire.
Builders chase tuck for different reasons. In shakotan and old-school Japanese styling, deep tuck under a rolled or pulled fender is the point. On daily-driven cars, a little tuck is the safe setting: nothing rubs on compression, nothing throws road spray down the side of the car, and most states have laws requiring the tire to be covered by the fender. Between tucked and poke sits flush, where the wheel face lines up almost exactly with the fender lip.