Stock Subaru wheel offset is between 45mm to 53mm. The +45mm offset will have a similar fit to stock Subaru wheels but isn't enough to clear the calipers in a 16" wheel. By adding the 1" (25mm) wheel spacer you will be creating a +20mm offset allowing the wheel to clear the caliper but potentially could cause interference with the fender depending on what size of tire is being run
What is wheel offset?.
The offset of a wheel is the distance from its hub mounting surface to the center line of the wheel.
Zero Wheel Offset.
The hub mounting surface is in line with the center line of the wheel
Positive Wheel Offset.
The hub mounting surface is in front (more toward the street side) of the center line of the wheel.