wheel spacers

i just bought some new 18" katana vr6's, and I'm having issues w/ clearance in the front. The spokes on the rim is rubbing against my brake caliper. Even w/ the wheel spacers they sent me, it still slightly rubs. Offset of the wheels are 40mm, and size spacer is 1/4". They told me to go 1/8" but do you think its safe? Anybody know who makes spacers specifically for the tC? any info would be good, I just want my rims on!

Heres a sneak peek of what they look like on...