The typical size for the concrete base is 18" x 18"
Option 1: Concrete is flush with driveway. Anchor is set as close as possible to driveway. The hoop's overhang from the backboard to the edge of the driveway will be between 2'6" and 3' when the basketball hoop is raised to the regulation height of 10'. If the hoop is lower than 10', the overhang will increase.
Option 2: Concrete is flush with driveway. Anchor is set back 15" and hoop is approximately 12" from driveway. The hoop's overhang from the backboard to the edge of the driveway will be between 1'6" and 2' when the basketball hoop is raised to the regulation height of 10'. If the hoop is lower than 10', then the overhang will increase.
Option 3: Concrete is not flush with driveway. Anchor is set back 27" and hoop is 24" from driveway. The hoop's overhang from the backboard to the edge of the driveway will be between 6" and 12" when the basketball hoop israised to the regulation height of 10'. If the hoop is lower than 10', then the overhang will increase.