I can see that for these wheels, you ended up freehanding the ellipses. I will factor that into my feedback - as noted in the assignment section, I do strongly recommend that students get their hands on a master ellipse template (full ellipse guide sets are prohibitively expensive, but these are more affordable), simply because it helps eliminate the added complication of being able to pull off freehand ellipses that are accurate and even enough, which is even at this stage understandably difficult.

Anyway, jumping right in with your construction, generally I can see that you've put a fair bit of consideration into the various ellipses that would make up the "profile" of a given wheel structure, with plenty of cases where you've included more of a bulge through the midsection to capture the appearance of something "inflated" rather than totally rigid. You are also fairly consistent in building out not only the face of your rims (the portion that points outward from the center of the wheel), but rather also included the side planes of those structures to flesh them out entirely. While the spacing wasn't entirely perfect, I felt the implied planes of these forms, where you left the internal edge out but conveyed them through the silhouette/edges of the form was quite well done.

Continuing onto the second part of this challenge, where it becomes more of a "trap" to catch those who've entirely forgotten the textural principles from Lesson 2 (given how far removed we are from it), you have indeed remembered to think about how to convey many of these with implicit drawing techniques, but there are some ways in which your work here can be improved.

There are 2 main strategies I'm seeing from you, on how to tackle these tire treads. The first is to employ full construction, building out each and every textural form, then to draw the shadows they cast. On one hand, this does result in you approaching your shadows more correctly - at least in part - but the downside is that you're locked into such a high level of detail density, that it draws the viewer's eye. That may be fine if we're looking at a wheel floating in the void, but as soon as you use these as part of a car, the viewer's eye is going to snap right to the wheel, whether you want it to or not.

As shown here, purely implicit drawing techniques can allow us to control how much ink we put down to convey a texture, without changing the nature of the texture itself.

The other strategy attempts to work more implicitly, as seen here, but doesn't actually involve drawing any cast shadow shapes. Instead, you're filling in the side planes of your textural forms, which is more similar to applying form shading instead. This is also a sort of explicit markmaking, because we're still locked into filling in predefined surfaces completely - we can't reduce or expand those black areas. You actually do end up with situations where you combine this with the first strategy, resulting in fully constructed forms who have some manner of form shading on them, sometimes combined with cast shadows as well.

Basically, if you're not designing a new shadow shape, rather than filling in a surface that's already there, then you're probably just filling in the side plane with form shading.

Now, it's understandably easy to get form shading confused with a cast shadow, and it happens to plenty of students. Here's a diagram I drew on another student's work to demonstrate the difference - which is actually quite subtle.

On the top, we've got the structural outlines for the given form - of course, since we want to work implicitly, we cannot use outlines. In the second row, we've got two options for conveying that textural form through the use of filled black shapes. On the left, they fill in the side planes, placing those shapes on the surface of the form itself, and actually filling in areas that are already enclosed and defined on the form and leaving its "top" face empty. This would be incorrect, more similar to form shading and not a cast shadow. On the right, we have an actual cast shadow - they look similar, but the key point to pay attention to is shown in the third row - it is the actual silhouette of the form itself which is implied. We've removed all of the internal edges of the form, and so while it looks kind of like the top face, but if you look more closely, it has certain subtle elements that are much more nuanced - instead of just using purely horizontal and vertical edges, we have some diagonals that come from the edges of the textural form that exist in the "depth" dimension of space (so if your horizontals were X and your verticals were Y, those diagonals come from that which exists in the Z dimension).

So, that is something you can certainly continue to work on, but all in all you're progressing well. I'll go ahead and mark this lesson as complete - and if you can, it would be in your best interest to pick up a master ellipse template for Lesson 7.