I was making the tutorial from BlenderNerd here : http://blendernerd.com/create-a-tire/
When I rendered the image, strange black things appeared in the original model, but not in the others which I used the array modifier to create.
http://dl.dropbox.com/u/15046364/untitled.png
Could these things be shadows?
Thanks in advance.
Remove doubles (W key > Remove Doubles) and if that doesn’t work, try recalculating normals. (tool shelf)
I’ve tried both already with no difference…
Start over 
post a blend file or a wireframe picture. It looks like you have overlapping faces
Remove doubles doesn’t work because the array modifier is still active. So either apply the array modifier and then remove doubles, or tweak the settings of the array modifier by lowering the count, or change the rotation of the object offset
