Starting with the structural aspect of your wheels here, for the core body of each wheel you've done a good job of establishing the different circular cross-sections with your ellipses. One thing I would suggest accentuating a little more however is the size of the cross-sections towards the center of the wheel. This widening through the middle, which provides more of an arcing profile to the wheel as a whole, helps to convey to the viewer that the tire isn't just made of solid material that, if dropped, would land with a heavy thunk. It makes it appear more inflated, more like it would bounce.

We can see this a little in some of your wheels - for example, the bottom right of this page, although many of your others tend to be much straighter across. I talk about this in this step.

Another point I wanted to call out is that when it comes to the rims/spokes in the center of your wheel, you constructed them for some of your wheels, but for the vast majority of them you seem to have skipped and focused only on the tire. Do not modify the instructions - focus on executing them as they're written, without any deviation. This challenge has us drawing entire wheels because they both contribute in different ways.

For the cases where you did include the spokes/rims, I did see you struggling a fair bit with the smaller size of the wheels. I still think you made the right call drawing that small, as I suspect the reason was that it allowed you to use an ellipse guide. That said, when it comes to dealing with smaller drawings, we simply need to give ourselves more time. By their nature, they feel like we're accomplishing less, and so it really flares impatience, but ultimately the choice of whether we rush through our linework as we see here, or if we take our time in executing each mark as we see here, falls to us.

Additionally, there were cases where you focused only on establishing the outer face of the spokes, as we see here. Don't forget to also establish the side planes of those structures, as this is necessary to make them feel solid and three dimensional.

Continuing onto the textural aspect of this challenge, this is a section that serves as something of a trap. Being as far into the course as we are, it's very common for students to allow certain concepts we introduced earlier on in the course to slip from their memory, and the most common section for this is Lesson 2's texture section where we discussed the difference between implicit and explicit markmaking, and discussed how texture is to be conveyed not by drawing forms directly, but rather by drawing the shadows they cast on their surroundings.

You certainly have fallen into this trap. Mainly what I'm seeing here is that you've focused either on drawing your textural forms through constructional means, outlining them as we see here, or on focusing what you see from observation, but drawing what you're observing directly (instead of considering what you see tells you about the textural forms that are present and how they sit in space, and using that to inform how your cast shadows are designed). As explained here in Lesson 2, the manner in which we design the shapes of our shadows matters a great deal, as it's this shape which establishes the relationship in 3D space between the form casting it, and the surface receiving it. Some students confuse this for simply filling in existing shapes in their structures (like the side planes), but this is more akin to form shading, which as discussed here, we generally avoid in this course. A good rule of thumb is that if you find yourself filling in a shape that was already present, rather than designing a new shape, take a step back and ask yourself whether what you're drawing is a shadow being cast or not.

When it comes to textures that involve shallow grooves, holes, or cracks - and there are many tire tread textures that are made up only of shallower grooves - there's another reason why it becomes significantly easier for a student to end up just drawing what they see, and drawing those grooves directly as lines, rather than considering the small forms being represented and thinking about how they relate to one another in 3D space. Many textures are "named" after the kind of forms they're composed of. Bumpy textures have bumps, rocky textures have little rocky protrusions, etc. and these names correspond directly to the textural forms that are present. With grooves, cracks, and holes on the other hand, the words used to label them don't actually correspond to the textural forms. Instead, they correspond to negative space, where no form exists. Instead, the actual forms that are relevant here are the walls that surround those gaps, and it's those walls that cast shadows upon one another, and upon the floor of the hole below. I explain this further in this diagram.

Now, I'm generally very hesitant to assign revisions for this challenge. Normally the major issues present relate to the "trap" laid in regards to texture, and that isn't something I hold students back over. I am not going to be assigning revisions to you either, but I do want to make it clear that the fact that you neglected to draw the rims/spokes in most of your wheels is why I did consider assigning further revisions. Instead, I'll leave it to you to consider what concepts you may not have reviewed or practiced recently - including texture, of course - so you can ensure you're caught up on everything before moving onto Lesson 7.