Starting with the structural aspect of the challenge, I can see that you're making use of your ellipse template, and that you're likely working with a master ellipse template which is what we generally recommend - while it's not a perfect solution, it's far more affordable than a full set of ellipse guides. Because those master ellipse templates don't have a wide variety of degrees and sizes, they inherently do leave us with a choice between either using the same degree for the closer/farther ends of a wheel structure (despite that far end technically having a wider degree in an ideal world), or choosing a wider degree to get that degree shift, but in combination with being considerably smaller overall than the closer end, giving a much stronger impression of foreshortening than would be normal at the scale of a wheel. It's a compromise either way, and your choice here to lean into the more dramatic foreshortening is fine for our purposes here, although when practicing this exercise in the future, it's worth trying to see how it turns out using the same ellipse throughout - due to the fact that wheels usually aren't terribly large, it's often quite workable as well.

When it comes to the spokes of your rims, your work is somewhat mixed, although rather than being a sign of misunderstanding I think you might just not be giving yourself enough time to ensure that these are drawn out in their entirety, and to ensure that you're thinking through the spatial relationships between the different elements. Rather, instead of thinking about each individual form being added as it exists in 3D space, you may be focusing more on simply copying what you see. For example,

• Here you skipped out on defining the side planes of many of your spokes, and also would have benefited from extra planning to ensure your spokes are spaced out more evenly

• Here you skipped constructional steps in building up those more complex two-pronged spokes.

Continuing onto the textural aspect of the challenge, this is an area where many students fumble, and by design. Being as far removed from Lesson 2, where we introduce how we engage with texture in this course, specifically through implicit markmaking (that is, drawing the shadows textural forms cast on their surroundings, rather than the forms directly), it's very common for students to forget those concepts and require a refresher, and so by assigning a heavily texture-focused exercise here, we can provide a much more poignant reminder that students should perhaps go back and review that material, as well as anything else they may have allowed to slip through the cracks and that might merit some extra attention.

Implicit markmaking is important both because it hinges on the same spatial reasoning this course focuses on. The shadow shapes we design based on the information we observe from our reference images, rely on us considering how those textural forms exist in 3D space and relate to those around them (as discussed here in these reminders from the texture section), and so just as the intersection lines between forms define the relationships between structures we might construct through explicit markmaking (outlining and other forms of direct representation of those forms), the shapes of our cast shadows allow us to convey relationships between forms that we don't draw as directly. This also provides a foundation upon which we can base our choices when we try to imply details - that is, where we're not necessarily trying to pack a drawing full of detail (which can create unintentional focal points, drawing the viewer's eye whether you mean for them to or not), and are instead relying on the viewer's brain to fill in the gaps.

In order to achieve that, the marks we do put down have to follow a logic that the viewer's brain can latch onto and understand (in order for them to extrapolate from it), so using cast shadows, which adhere to general physical rules/properties that the viewer will already be well accustomed to as an observer is an effective approach.

One last point on this topic - when it comes to those tires with shallow grooves, or really any texture consisting of holes, cracks, etc. it's very common for us to view these named things (the grooves, the cracks, etc.) as being the textural forms in question - but of course they're not forms at all. They're empty, negative space, and it's the structures that surround these empty spaces that are the actual forms for us to consider when designing the shadows they'll cast. This is demonstrated in this diagram. This doesn't always actually result in a different result at the end of the day, but as these are all exercises, how we think about them and how we come to that result is just as important - if not moreso.

Now ultimately in the work for this challenge, you haven't worked with implicit markmaking at all, but rather put down your textural marks based on direct observation, identifying specific marks and then transferring them directly to your drawing (so in terms of the reminders linked above, you skipped over the "understanding" stage where we consider the textural form in question and design a shadow shape to represent its relationship with the surroundings). That's not something you'll be assigned revisions on (as this is an intentional trap for students to stumble into), but it is definitely a sign that you'll want to review that implicit markmaking material from Lesson 2 as well as anything else you may have allowed to slip through the cracks along the way, before finishing up the rest of the course.

I'll leave you to that, and will go ahead and mark this challenge as complete.