Wheel offsets

[KungFuPanda]

I currently have an Audi S6 with 19" wheels with a width of 8.5" an an offset of 45.

I'm looking at changing them to a 20" wheel width of 9.0" and an offset of 42.

Does this mean that the inner face of the wheel will be 3mm closer to the hub and brake caliper because the offset is 3mm smaller? I only ask because the gap between wheel and caliper is tight enough on the existing 19" wheels.