I honestly don’t know the offsets. I know they’ll fit flush with the fenders.
On 18x8.5F they usually run a +40, then on an 18X11R, it’s a +28. They don’t show the offsets anywhere on the wheels as they’re a true 3-piece race wheel. On the side pic wheel you can see the barrels, you’ll see that one says 8.5 as that’s the size from the inside of the bead to where the pieces meet. The other side is 3".