I am making tread for a car and I made a simple pattern for one section and then duplicated it a bunch of times using an array. What I want to do now is take the model that is flat and wrap it around an axis to turn it into a wheel. How do I do this?
One way is to just add an Array modifier to your tread or flat object, bump up the counts a bit and add a new Bezier Circle to the scene.
Then add a Curve modifier, select the correct axis (it sometimes wacks out here, you can just apply transformations before you do this) and tweak accordingly until it aligns properly and is arched around a portion of the curve.
Bump up the array count some more and voila, a tire or whatever object wrapped around a circle. (When doing this, you might have to select the curve and scale it accordingly so that the ends of the object meet. You can also tick 'Merge' in the array modifier or use Alt + C to apply the modifiers and convert everything into one object, after this, if a gap still exists, it can be easily filled.
Let's not forget the grandfather: Warp
In edit mode, position the cursor where your axle is supposed to be, select the mesh and hit SHIFT+W. Make sure that your line of sight is parallel to the axle because Warp takes the orientation of the 3d view into account.
This is useful if your mesh contains other parts or you are just too lazy to use modifiers and later change is not necessary.
Use numerical input and finisch the modifier with 360RETURN to get a full circle.
If you want a precise diameter, position the cursor on an outer vertex with SHIFT+S3 and then use the 3d cursor panel to move it down (or move the mesh up with numerical input)
There are a variety of ways of doing this, but one of the simplest is just to use the Array modifier with 'Object Offset'.
Model the object you wish to wrap around and place an empty where you want the center of your wheel to be located. Place your object's center at the same location as the empty (ShiftS>Selection to Cursor (Offset)). Add an Array modifier on your object and select 'Object Offset':
Rotate the empty very slightly, and bring the array count high enough, and the array should wrap all the way around in a circle.
If you want to do further smoothing, you can apply the Array modifier, then use all of the usual tricks (subdivision surface, smooth lighting, Boolean union, etc).