Backspacing is the distance from the back edge of the rim to the part of the wheel that touches the drums. If you had a b.s. of 1", your wheel would stick past your body,If you had a b.s. of 8" the rim wouldnt even fit in your wheelwell without hitting inner fenderwell. so there is a range of b.s. that fits the rim properly to the car, this varies from car to car.