the only thing i could suggest as for the rim, and im assuming you used the rim tutorial on the net, is that the lip of the rim ends by the spoke.
in a real rim, the spoke would not be open at the back, they would be closed and the inner rim of the lip of the wheel would continue on to the far inside of the wheel instead of stopping a few inches in.

if you aren't sure what im talking about i can add a picture.

and the lug nuts and lug holes look far too small to be correct proportion to the rim, the only way that would be proportioned right is if it was a 40" rim.

and the outer ridge on the rim is usually needing to be a harsher edge on it rather than a rounded edge.