Wheel backspace and offset measurements help in tire installation and increase vehicle track width, thus improving stability. The measurements are important when choosing wheels, tires and fenders for different car models.
Backspace determines how much of the wheel protrudes inboard beyond the rotor and towards the suspension components. It ensures the wheel and tire have plenty of space to clear suspension.
Offset determines the best position for the wheel to sit by specifying the location of the hub mounting surface relative to the overall width of the wheel. When combined with tire width, offset influences the vehicle's stance. Zero offset eliminates steering difficulties and wheel bearing fatigue.