I think this is the first time I've seen a student fit all of their wheels onto a single sheet. In retrospect, I imagine most of them had wheels small enough to do so (mostly because of their ellipse guide limitations), but I think most people have been too nervous to have everything on the same page, lest they screw something up. It's always nice to see the kind of confidence you've demonstrated here, so well done on that front, even if it wasn't strictly part of the exercise.

It definitely would have been helpful to have the wheels be numbered so I could point to specific ones more easily, though.

Starting with the core constructions of your wheels, you've done a great job. Not only are you putting that ellipse guide to good use, and actively building each wheel/tire with a number of different ellipses rather than just a simple cylinder, you're also taking care to respect the three dimensional nature of the rims/spokes by being thorough and drawing each one's front and side planes appropriately, even when that kind of detail gets very tight and cramped.

One little reminder in that regard - careful with cases where you end up filling in the side plane with solid black, as you did for the rims on the bottom right corner wheel (along with a few others). This has a tendency to separate the form itself into distinct pieces, and in so doing, makes the section that wasn't filled in appear more like a flat shape. You can see this demonstrated in this example - notice how on the left side, it appears more like we're looking at a flat white plane, and while our brains eventually register what the black stuff around it is meant to represent, it's the right side example that'll convey more quickly and more effectively the impression of a solid, cohesive box. There the filled area of solid black is used strictly for the shadow the form is casting, which also has the bonus of defining how it relates to its surrounding surfaces.

That is ultimately what brings us to the second section of the wheel challenge - capturing the texture of the tire tread itself. This is something that exists here as a bit of a trap. It's normal for students to feel so far separated from Lesson 2's texture section that they've forgotten its principles, so this challenge works as a bit of an unexpected reminder.

Ultimately, as discussed in Lesson 2, texture - which is any arrangement of forms along the surface of a larger object, so that definitely includes tire treads - is captured strictly through implicit means, by defining the shadows these forms cast, rather than outlining or drawing the forms directly. Cast shadows themselves are specifically the independent shape that is cast from the form in question onto another surface.

I say "independent" shape because cast shadows will generally require us to design a completely new shape, rather than simply filling in an existing space or plane in the existing structure - that's why filling in the side planes of a form, as we discussed before, doesn't constitute adding a cast shadow. In fact, it's more similar to form shading, because one plane is darker based on its orientation relative to the light source - and as discussed here, form shading isn't something we're incorporating into our drawings throughout this course.

Now, the textural issues in this challenge usually come out most prominently when we deal with the "chunkier" tire treads that we see on things like tractor tires, and I'm not really seeing any of those here (you weren't instructed to play with them in particular, so that's not a mark against you). When it comes to the tire treads with shallower grooves, texture tends to be more forgiving. There is however one thing even in this kind of tire tread that I want you to avoid.

If you look at this wheel in particular, along its central strip, there are a bunch of lines that kind of criss-cross across the tire's surface. You drew each of these lines from end to end, treating it more like a visual pattern along a flat surface. Remember, however, that all texture is made up of actual concrete forms, and it's those forms that you need to be consciously aware of - not the negative space, cracks, or grooves in between them. So rather than seeing lines and drawing lines, you should be seeing those lines and asking yourself what that tells you about the forms around them. It's that which will help you think more about the actual shadows cast by those forms.

At the end of the day, the textural techniques shared in Lesson 2 are important because of the control they give us. In your drawings, you were by and large forced to capture all of the different details of each tire tread, in their entirety, covering the whole tire. As shown in this example however (which isn't of a tire - they're actually african bush viper scales), capturing texture through implicit means allows us to control exactly how much ink and how much contrast will go into a certain section of a larger drawing. After all, in this challenge you're working with individual wheels - but if you're drawing a whole scene, being forced to include all of the tire texture into a tiny section will result in a very high contrast, very eye-catching section. It'll result in a focal point where you do not mean to include one, which in turn will mess with your ability to control your composition and the way the viewer's eye navigates through it.

So! As I mentioned, this "trap" is something many students fall into. It's not something to assign revisions over, and as a whole you're still doing very well. It's just a bit of a reminder, so keep it in mind as you move forwards. I'll go ahead and mark this challenge as complete.