I notice it when I use the multi-pass renderer too. It doesn't show up when I use the A-buffer at all.
The outer rim of the skateboard has just a diffuse color with a reflectivity value of 100%.
The group on the inside has a diffuse color, and an ambiance intensity of 100% and material setting is set to a Sine turbulance.
The first attribute has diffuse, ambiance, and specular colors, ambiance is set to 40%, specular size is set to 78.38%, and it has a roughness of 20%.
The second attribute has diffuse, ambiance, and specular colors, ambiance is set to 50%, specular size is set to 100%.