Gplexus

Hey everyone I'm new to the family and looking to upgrage from the 17" OZ rims that came on my 2IS. Im thinking the tsw Bristol. My question is if I go with staggered 18x8.5f and 18x9.5r. The 8.5 comes in 20, 30, and 40mm offset and the 9.5 come in 20 and 40mm. What combo will give me a flush look ? I'd like to go 18x8.5 40mm in front and 18x9.5 20mm rear. Btw the car is just being dropped on springs when I do the wheels so nothing too low.