Thanks for your comments. The tyre is not perfectly black as it's not in a showroom so there is dirt on it. I agree that the background might be improved with a little less sharpening.
a few suggestions: i feel the tyre should be black, frank. or almost black. it's very noisy/mottled at the moment. you might want to exclude the background from your sharpening techniques, as it's a little too aggressive on the gravel and shadows. and i'd crop tighter bottom and right (the tyre) to give it a more abstract feel and put the focus on the chrome wheel trims. bugzie
