Jumping right in with the structural aspect of your wheels, overall you're handling it quite well. You've built out the body of your wheels with separate ellipses for the sides/middle, allowing you to widen the center and create the impression that the tire itself is inflated, and that it would land with a bounce rather than a heavy thud. You're also mindful of the side planes of your rims' spokes alongside their front facing faces, which helps to create a more solid structure. The only criticism I have there however is that for the purposes of this course, you shouldn't be filling in those side planes with black, as this is more akin to form shading, which as discussed here is something we don't want students worrying about here.

Carrying forward into the textural aspect of the challenge, this is admittedly something of an intentional trap. Being as far removed from Lesson 2 as we are, it's pretty common for students to forget about the principles of implicit markmaking we discuss there as being the primary tool we use for conveying texture. Since texture is essentially forms running along the surface of an existing structure, tires and their treads fall into this category, though it's easy for students to forget this - whether partially or entirely. In your case, it's clear that you did pick up on the textural aspect of this, and that you also did make clear attempts to try and figure out how to convey texture through the use of filled areas of solid black (at times relying on outlining the textural forms first, and in some other cases like number 11, trying to figure out how to work without those outlines, which is certainly a move in the right direction), but ultimately you did still end up applying largely explicit markmaking techniques, rather than implicit.

Basically it comes down to this - we can draw a very detailed wheel, with every bump and protrusion in the tires fully outlined and constructed, resulting in a very dense level of detail, and that will look fantastic when floating in the void, as our wheels do here. But if we need that wheel to serve as part of a larger illustration, then it creates a problem - with all that density of detail, it creates a focal point that draws the viewer's eye, whether we mean for it to or not.

Implicit markmaking is all about cast shadows - the idea that instead of drawing each bump or protrusion individually, constructing it with outlines as we would any other normal structure (which results in that visual density), we can instead draw the impact it has on its surroundings. That is, the shadows it casts on those surfaces around it. The thing about cast shadows is that they allow us far more flexibility.

As shown in this diagram, depending on how far the form is from the light source, the angle of the light rays will hit the object at shallower angles the farther away they are, resulting in the shadow itself being projected farther. This frees us up to choose whether we want to leverage larger shadows that blend into one another, shadows of a middling size that cause a greater balance of light/dark (this is where we get more detail density), or smaller/negligible shadows where the light source is so close that it blasts them away entirely in certain areas. And, as shown in Lesson 2's texture analysis exercise, we can choose to shift from one to the other. It's less about worrying about where the light source actually is in many cases, and comes down more to the fact that because it's possible, it gives us more control.

Of course, working in cast shadow instead of filling in the side planes with form shading is definitely a mental shift that can be quite difficult for students, because it takes a good deal of practice to be able to identify how to place a cast shadow without the form casting it first being constructed - but as with all things, it gets easier the more we do it. It's also not "THE" way to handle texture - it's a very useful way to learn how to approach implied detail (where artists will flesh out parts of a texture but leave other areas blank or sparse to be filled in by the viewer's brain), and it relies on the same spatial reasoning skills this course as a whole focuses upon, making it a perfect choice for our work here.

One last thing 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, I am certainly going to mark this challenge as complete - most students ultimately fall into the same trap, and so I do not hold it against them. Rather, I use this as a reminder for students that they my wish to reflect on areas of the course material they may have allowed to lapse or fall through the cracks, so they can go back and review those sections before finishing up the course.