Front tread is the distance between the center of the left front wheel and the center of the right front wheel.
Rear tread is the distance between the center of the left rear wheel and the center of the right rear wheel.
Gross weight is the total weight of an automobile when fully loaded with passengers and/or cargo. The difference between Gross Weight and Kerb Weight is the total passenger and cargo weight capacity of the vehicle. It is also called Laden Weight.