Tire Tutorial (Maya)

 

This tutorial shows how to construct a tire for a small motorcycle

but can be extrapolated for any other tire.

This tutorial assumes some basic Maya knowledge.

1. Using reference work out what comprises the tire pattern and break it down into the unit of itís repeating pattern.

2. Then work out the shape of a tile of that pattern that will interlock.

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3. It could be easier to work it out in the 3D package: Work in the top view initially.

††† Go to Create> Polygon Primitives > Plane. In the channels box make the height and width even numbers (4x6) and give it 6 subdivisions in width.

4.†† Then move the vertices using Snap to grid (Hotkey x) to create the tile. If you end up with an edge that distorts another edge be sure to delete it using Polygons> Edit Mesh> Delete Edge/Vertex or the remaining vertices will distort the line.

5. Go to Polygons. Edit Mesh> Insert Edge Loop and place 3 loops to form the basis of the tread. Move the vertices to improve the shape. Go to Face mode and Shift select the faces of the tread.

6. Go to Polys> Edit Mesh> ExtrudeĖ making sure that Keep faces Together is ticked. Move down slightly in Z. If the result is a bit strange undo and click the small blue circle to the top right of the extrude tool. Have a look at the result in the perspective view and adjust. Further adjustment can be done with the Scale Tool

 

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7. Go into Object Mode and select the tile and Duplicate (Ctrl d). In the Channels box make the Scale X value minus. It should now read Ė1 and enter. This will flip the tile to itís mirror image. Now move it so that it locates to the other tile.

 

8. Combined the two tiles : Select both tiles. Mesh> Combine. The edges of the two pieces have to be merged now† but before they can some geometry has to be created where the treads locate to create the herring bone pattern.

Go to Edit Mesh> Split Polygon Tool create a small rectangle where the tread of the other tile touches. Select it and delete. It doesnít matter if it is not exact. Move the vertices using Snap to points (Ctrl v) to line them up along with any other points that donít marry up.

Now merge: Select corresponding points on both tiles and Edit Mesh> Merge until all the edges are joined

9. Using Edit Mesh> Split Polygon Tool put a line that will cut across the whole tile. Select the polygons one side of the line and go to Mesh> Extract. Make sure that Separate extracted faces is unticked and apply.

Move this band to the other side of the tile.

Theoretically to get it to line up exactly you can enter 4 into the Translate Z Channel.

Using the technique in 8 join the two pieces together though they wonít have to be combined as they are still the same piece of geometry. This stage is to aid bevelling later.

Notice that the pivot is not centered so in object mode go to Modify> Center Pivot.

10. To bend the geometry go to Animation> Create Deformers> Nonlinear> Bend.

††††† This will apply the deformer but it will be in the wrong orientation. So in itís Channels rotate it 90 in Z. Then under INPUTS click on Curvature and middle mouse drag in the view. This will cause the geometry to bend. Bend to suit. I do this by eye.

11. Select all the uncurved boundary edges. Unless you have torn off the Edit Mesh menu go to Polygons> Edit Mesh> Extrude and with a series of extrusions make the tire wall unit. This tool will have to be reoriented each time by click the small blue circle.

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11. A tip here is to go into subdivided mode to check that all edges are joined. Notice how the rounding reveals a gap. A line of polygons can be selected and moved to reveal how far the edges arenít merged. Ctrl z to put them back in place and merge (Step 8).

 

12. Bevel the tread. Select All the edges of the tread except perhaps the corners. It does to be really diligent zooming in to pick them all up.

Go to Edit Mesh> Bevel. Subdivide (3) to see what it looks like. It is probably a bit too rounded. Change the value in the Channels> INPUTS> polyBevel> Offset down to about 0.2 or less.

 

Return to undivided (1)

 

13. Measure the geometry (it may not be exactly 4 units now). Go to Create> Measure tools> Distance Tool and Snap to Point select a vertex and then the equivalent one on the other side of the geometry. This will then show the distance.

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14. Duplicate the segment. To get the right number of segment at the right distance go to Edit> Duplicate Special put the measured figure in the Translate Z box and 39 in the Number of copies box and Apply.

Select all the geometry and Combine (Mesh> Combine) Box select it all again in Vertex mode and Edit Mesh> Merge. Press 3 to check if it has merged. It might be an idea to make a UV map at this stage for texturing.

15. To bend the tire first of all Center Pivot (under Modify). Then Animate> Create Deformers>† Nonlinear> Bend. The deformer will not only have to be relocated in Z rotation but X as well. So enter 90 in both or the tire will bend sideways.

Highlight Curvature under INPUTS> bend and Middle Mouse drag. The value will be of a minus value. Theoretically it should be around pi (3.142) but may need some fine adjustment in the value box. There is a way of doing this involving measuring† and an obscure value box which I canít find (Deformer control length?).

Select edge points and Edit Mesh> Merge.

In object mode go to Modify> Center Pivot.

Then Edit> Delete by >Type> Delete History to get rid of deformers and mesh history.