Starting with the wheels' constructions, you're generally handling these well, but there are a couple areas where I can provide some suggestions to help you continue to get the most out of these exercises.

Firstly, don't be afraid to add a bit more of a "swelling" through the midsection of the wheel itself. I can see that you're using several ellipses to create the general profile of the structure, but all of them tend to have a pretty straight run through their middle. Instead, if we take the center ellipse and scale it up a bit, we get a nice bump that helps make the tire feel a little more "inflated".

Secondly, when it comes to the rims themselves, your linework gets admittedly... rough, and there's no real reason for this. Every mark we put down still needs to be thought through, using the ghosting method. The ghosting method is really more about just forcing students to think before they draw, to figure out what specific task each mark is meant to accomplish, and to execute each one with one mark. It seems here that you let yourself get a little sloppy, putting marks down without as much thought and sometimes putting more than one mark down where just one would do the job.

All that said, I am pleased to see that you're not limiting yourself only to drawing the face of the rims - you're also including the side planes to ensure that those structures still read as three dimensional and solid.

Now, the second part of this challenge is admittedly a bit of a trap. Being as far removed from Lesson 2, it's pretty common for students to basically forget about the principles of texture and implicit markmaking. Unfortunately, it does seem you fall into that category - you made a point of constructing and outlining each and every textural mark in its entirety, rather than applying the approach laid out here.

One thing to consider is the fact that all this dense linework creates an unintentional focal point. While this may not be an issue for wheels that are floating alone in the void, but when we look at drawing a whole car, it means that the viewer's eyes are going to jump straight to the tires, whether you want them to or not. When we work implicitly however - drawing the shadows those textural forms cast rather than the forms themselves - those shadows are allowed to merge together, implying the presence of those textural forms through the way in which those shadows are designed, and allowing the viewer's brain to fill in the rest.

I did notice some spots where, after you'd outlined the textural forms, you applied some filled shapes more similarly to what we look at in Lesson 2, but these were not cast shadows - instead, you were filling in those textural forms' side planes, which is more similar to form shading. Here's a quick demonstration of the difference on another student's work. Along 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).

Now, while these points are important, and things you should definitely review on your own, I am still going to mark this challenge as complete. Rather than a reason to hold students back, I use this challenge more as a reminder to go back and make sure you're not forgetting things that were introduced earlier on.