Wheel experts...need advice...check my math.

[G Man]

I'm looking at a set of wheels for our '04 X5 4.8is. The factory wheels are 20x9.5" front (ET45, BS 6.52"), and the rears are 20x10.5" (ET30, BS 6.43"). The new wheels I'm looking at are 20x9" front (ET32, BS 5.75"), 20x10" rear (ET25, BS 6"). My thought is the the new set should sit further outboard (even with the wheel wells) with the lower offset / backspacing, or at the very least be close to the same, based on the .5" narrower wheels plus the lower offset. Thoughts??

Stock Wheel- Front
45mm = (45mm) / (25.4mm/in) = 1.77 in
1/2 Wheel Width = (.5) x (9.5 in) = 4.75 in
BS = (4.75 in) + (1.77 in) = 6.52 in

Stock Wheel- Rear
30mm = (30mm) / (25.4mm/in) = 1.18 in
1/2 Wheel Width = (.5) x (10.5 in) = 5.25 in
BS = (5.25 in) + (1.18 in) = 6.43 in
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New Wheel- Front
32mm = (32mm) / (25.4mm/in) = 1.26 in
1/2 Wheel Width = (.5) x (9.0 in) = 4.50 in
BS = (4.50 in) + (1.26 in) = 5.75 in

New Wheel- Rear
25mm = (25mm) / (25.4mm/in) = 1.00 in
1/2 Wheel Width = (.5) x (10.0 in) = 5.00 in
BS = (5.00 in) + (1.00 in) = 6.00 in