General: Colours are subtle which works to generate a mood for this image.
Composition: For the most part the composition works here, axle in top third. Though it might be a bit tightly cropped on the bottom and a bit loose on the left. There's also an interesting figure 8 pattern in the center of the wheel. This might make a cool image on its own.
Also, good choice of background. It looks like pavement even though you mention that it's black posterboard. It makes the wheel stand out, drawing the viewer into the image.
Exposure: Exposure seems bang on. The white wall of the tire is not blown out while the darker areas have just enough detail. The spokes are just visible enough to give the sense of motion.
Impact: Even though the wheel depicts motion perfectly, the image seems to be a little static. I wonder if the image would have more impact if it were more tightly cropped on the left but less on the bottom?
Congratulations on achieving the goal you set for yourself with this image and remember that in the long run, the opinion that counts the most is your own. Keep shooting.
For those who wondered, it was shot outside, -- shutter speed at 1/10 -- had my son hold black posterbord behind the wheel, then inverted the image-- from there just adjusted levels manually
Great shot, I wonder if centering the axle nut in the top left third intersection would make it more appealing, I will be interested to see what others comments are on this one.
This is a great photo - I suspect it will do well. The colours are interesting, the concept of speed/motion is conveyed well. The composition is interesting and lihting is wonderful. Well done.