Nice work on your wheels! I'm pleased to see that you picked up an ellipse guide - you don't need to worry about picking up a bigger one in the future. What matters is that it allowed you to focus on the core aspects of the challenge without getting distracted.

All in all you've done a good job, but I have just a couple things to point out. Firstly, I noticed that you did have a tendency to slip into a lot of use of hatching lines throughout this challenge. This is usually as a form of shading/rendering, which is something we actually discourage way back in Lesson 2 (in these notes). Because it ends up just being decoration in the context of our constructional drawings, shading/rendering has no place in the drawings you do for this course. Always remember that.

The other issue I noticed was that when you deal with some of your tire reads - specifically the chunkier ones - you ended up straying from the principles of how we approach drawing texture. This is actually the same issue as the first.. kind of. Instead of capturing the shadows cast by those textural forms (the big chunky tire tread), you basically separated the different planes of that form with shading along its side faces. The reason this isn't ideal is that it helps separate the planes of that form in isolation - meaning without creating any real relationship between it and the surface upon which it rests. Conversely, if we were to leave the internal silhouette of that form empty (allowing the silhouette itself to imply the different planes), and only use the filled shape to capture the cast shadow that falls on its surroundings, we'd still get a sense of how the planes are separated, but also better grasp the relationship that form has with the main surface of the tire.

To better understand this concept, take a look at this diagram. On the left we've got your approach - the planes are separated, top from side, but there's no relationship with the surroundings. On the right, we've got the approach I'm suggesting, which leaves the inside of the form totally empty, but as you can see we can still infer the different planes based on how the silhouette itself has clear corners. The benefit here is that he cast shadow itself falls on the area surrounding the form, showing us how the form relates to this other surface.

If we look at wheel 24, we actually start to get into territory where the approach of blacking out the side faces of those tread forms makes the tread itself appear entirely flat (rather than raised), because all we have are the top faces of those forms, with the space between them filled with solid black. The eye doesn't clearly know how to interpret that, so it risks coming off as just being stamped upon a flat surface.

The better solution here is actually complicated - because on one hand, we first leave the internal silhouette of each form empty (like the right side of the diagram I showed you), but then as we add more tread forms, they're going to be casting shadows upon each other. This results in that same kind of filled-in-black-space, with the only difference being the little glimmers of white that show through. It's that kind of subtle effect, where a few tiny pieces of the side planes are left blank, that makes it read as believably 3D.

Anyway! It's actually very common that students forget about this sort of textural aspect of the treads. When it comes to the construction of your wheels, your work is looking great. As such, I'll go ahead and mark this challenge as complete.