Using 46/46mm Light Bicycle rims. I have no data as to their aero capabilities, though they certainly look the part. But they are nice and wide and I ride them with 34mm Compass tires; the pairing is heavenly to ride. I've felt an influence on really strong crosswinds before, but it wasn't anything that ever put me in any danger of going off the road or anything. It was enough to feel it and react to it, but not much more. And that was with really strong crosswind gusts. With typical breeze I don't feel a think.