This is the first time in quite a while that I've seen a student draw large wheels for their wheel challenge, while still continuing to use an ellipse guide! Normally full ellipse guide sets are way outside of students' price ranges (they more often rely on the master ellipse templates which have more limitations on the sizes of the ellipse they allow), so I suppose I'll pour out a libation to your wallet this evening.

Jumping right in, you've done a great job in handling the construction of these wheels - not just the main body, but the rims/spokes as well. You've taken a good bit of time in constructing them each with care, and that's always good to see. I have a couple suggestions however:

• When constructing the core cylinder for your wheels, try to avoid creating a straight cylinder. Instead, incorporate a bit of a widening through the midsection as shown here - note how that middle ellipse is a little bigger, giving it a sort of "inflated" impression. Of course, the need for this will vary from wheel to wheel, with some being much stiffer and thus leaning more into a straight cylinders, and others needing this kind of inflation.

• I'm noticing a tendency to fill in the side planes of your structures with solid black, or with hatching - often the inner rim of the wheel, as well as the side planes of the spokes. Remember that as discussed here, form shading will not be playing a role in our drawings for this course, and any situation where you're making a surface darker based on its orientation does constitute as form shading. Reserve your filled areas of solid black for cast shadow shapes only.

And that brings us to the second section of the challenge - the tire tread textures. This is actually a bit of a trap - being that we're so far removed from Lesson 2, many students at this point forget the textural principles. Since tire treads are made up of a bunch of small forms (either individual tread chunk forms, or the forms that create the walls of the tire's grooves) that run along the surface of the larger structure, they are indeed good candidates for the use of textural techniques - specifically those of implicit markmaking.

When we outline all of our textural forms (like in number 6), we end up in the tricky position of not actually being able to alter the density of that texture - or rather, the amount of contrast or number of marks that are being concentrated in a specific area of our drawing. This means we can end up creating focal points that draw the viewer's attention without meaning to. Not really an issue when the whole drawing is just the wheel, but if we're drawing a car, you probably don't want the viewer to be unable to pull their eyes from the wheels. Unless that's your intent, anyway.

That's where implicit markmaking comes in - it allows us to control the density of our markmaking, without affecting what it is we're conveying to the viewer (in terms of the structure/texture that exists). We can see this demonstrated in this example, which looks at african bush viper scales. Not a tire, but a surprisingly similar problem.

Now, you have attempted to deal with this problem in a few different ways. You've got attempts like number 8 and number 18, where you still outlined and constructed every textural form, but attempted to employ filled areas of solid black. Unfortunately, similarly to the point I raised earlier, here you're falling more into form shading rather than the cast shadows we want, because you're filling in the existing side planes - not introducing a new, separate, purposefully designed shape that defines the relationship between the form casting it, and the surface receiving it.

There are two strengths to cast shadows in this manner - first the spatial relationship they define between forms, and second the fact that they can continue to do this while merging with other neighbouring shadow shapes as needed. It's the specific design of that eventual amalgamated shape (which is just made up of a bunch of smaller, specific shadow shapes) that continues to imply the presence of forms, enough to get the idea across to the viewer.

There is further improvement across the set, however. Towards the end, with wheels like 22 and 25, you get much closer. In fact, I'd go so far as to say that 22 is pretty much correct. The reason 25 is not is that it focuses primarily on the grooves themselves, rather than the forms around them. The difference seems small, but basically we don't want to be filling in "spaces" - we want to ensure that the marks we put down for our textures are their own distinctly designed shadow shapes. Sometimes the result is actually the same - but making the distinction in your mind of what you're doing (filling in grooves vs. considering the forms that stick out around them, and the shadows they cast into those grooves) is what will help you get a better grip on how to think about texture in general.

Anyway - when it comes to the trap I set, you did fall into it, but not as completely as some students do. I'm pleased to see that you're making efforts to figure out how to apply those kinds of principles here. Regardless of that, this is not something I hold students back over - the trap itself is only intended as a sharp reminder to review that section from Lesson 2.

So! I'll go ahead and mark this challenge as complete. Keep up the good work!