Modeling the tires

Before we start modeling we take a look at some reference images, like these:

    
Look at the pattern of the profile on the tire..   also note the decreasing depth at the side!

We take the second image and use that as a background image for our modeling process. Make sure you have saved the Lamborghini project so you can clear the scene and start a new one. In front view, create a square analytical rectangle (press and hold the Shift key while creating the rectangle to make a perfect square), open properties at the Col tab and set the reference image as texture for the rectangle. Then go to the Wire tab of the properties and set Texture quality at 512 or better. Make sure you are working in OGL display mode, so you can see the texture on the rectangle.

Next, create a polygonal SDS Rectangle and place that at the centre of the tire. Like always, we model half and create the other half using mirroring. Switch to Face Edit mode and select the face. Then use the Knife tool (the one next to the Dupl. E tool), to add eight (8) vertical edges in total. Each edge creates a new face, which we later use for the profile of the tire. To get a nice vertical edge set the following options and press and hold the Shift key before you click to finish the tool:

The Knife tool and the options you need

Remember that you can use the Again function (press right mouse button in the View window and select Again from the pop-up menu, or press the 'a' key) to repeat the tool with the same settings as before.

For the position of the rectangle and the vertical edges see the next image:

Eight vertical edges added with the Knife tool

Repeat this process to add six more horizontal edges, like shown in the next image. To add the edges, you first need to select all faces you wish to cut. To get the same view as in the next image, select the SDS rectangle, open Property window at the Wire tab and set the 'No shading' option.

And six more horizontal edges added...

Then start moving points around, to roughly match the profile of the tire:

Profile roughly matched

The next step is to select all faces that need to be extruded downwards (the grooves in the profile). Switch to Face Edit mode, select the required faces and extrude these downwards. In the next screenshot you can see which faces you need to select (they all have a red dot):

Select all these faces and extrude them downwards..

Next, delete all faces that cross the profile grooves. See next image to see the faces you need to delete:

Delete selected faces as shown here

Also, delete the faces that are on the inner side of the tire, like shown in the next image:

Also delete these faces

Switch to Edge Edit mode and move the lower, outer edges up, like shown in the next image:

Move lower outer edges upwards

Here is a screenshot showing the result of the last instruction (front view)

Front view of the profile

Switch to Point Edit mode and bend the profile a little, like shown in the next image:

Front view of the adjusted tire profile

Select all the edges at the side of the tire and start extruding them to add new faces. Remember: select the edges, press and hold the Ctrl key to add new faces!

Select these edges and add new faces

The grooves in the profile now should be getting less deep. Switch to Point Edit mode and move the points that make the grooves. Level these points with the other ones. Where two points come together, use the Merge tool to join these into a single point.

Points of the grooves leveled and merged with the other points

Now the profile is reduced to zero, you can extrude the faces like you did before in Edge Edit mode:

Now extrude these edges downwards to make the side of the tire

Next screenshot shows the profile in front view after adding some faces:

Front view of the tire we have created so far..

Now it is time to set Edge Sharpness for the edges. Take a look at the next image to see which edges should be set to 'Sharp'; the other edges will keep the default edge sharpness.

All selected edges should be set to 'Sharp'

Now you can build the actual tire from the part you just created. Duplicate the object you now have and move it down and see how they fit together. Probably you will have to do some tweaking to match the two pieces together. When tweaking, remember to move the points in pairs to keep the groove width intact:

   
Duplicate added..                                                                  Tweaking done!

OK, after the tweaking is done, delete the duplicate object. Now the original object is ready to be duplicated and you can be sure the duplicates all fit together! Duplicate the original (adjusted) object again. Move the duplicate down and make the two objects touch. Then select both objects and apply the 'MergeO' (Merge Objects) tool. The two objects become one in the hierarchy and get the name of the first selected object.

Now save your work!

Next, in Point Edit mode, select all points at the intersecting area of the (former) two objects. See next screenshot:

All points at the intersecting area selected

Then apply the 'JoinF' (Join Faces) tool. In the tool control bar, set the Distance parameter to a small value (actual value depending on the distance of the two objects, the value shown in the screenshot may not be accurate for you). All faces whose edges have a distance smaller then the value you have set, will be connected. If you set your distance parameter too large, you may end up with more faces joined then you would like. So experiment with some values and make a simple test render. If the results are OK, then save your work. If not OK, then undo your last actions and try again.

Join Faces tool selected, Distance parameter set..

Repeat this process four times in total. The duplicated object doubles in size every time, so the profile object grows fast! You'll end up with a long string of profile parts all joined together. Then of course you have modeled only half the tire. A duplicate of this object will be used and mirrored. Finally they will be merged to make the tire complete:

   
Half a tire modeled then mirrored and merged

The last step is to apply the Bend tool (it is in the Transformation tab). Make sure you are in Face edit mode and select all faces. Press the F8 key to invoke the Numeric Window. Take a side view and start the Bend tool. Drag a box around the most left side of the object and then one around the most right side. Then simply enter 360 in the Angle field of the Numeric Window. The profile of the tire will bend perfectly.

 
Bend tool in the Transformation tab                                                             enter 360 in the Angle field

This is the final result after bending the profile:

Bend tool applied!

When done bending, the final step is to adjust the size of the tire, to match the size of the wheel and we are ready! Then duplicate the entire wheel three times to create 4 complete wheels, save your project and your car is ready to roll!

Test render of our wheel