Really nice work! Overall your wheel constructions are solid. You've clearly made excellent use of an ellipse guide (I'm honestly always incredibly pleased when people actually bother to get one - it makes things easier for everyone involved, and allows students to focus on the core concepts in the lesson instead of pinning down how to freehand their ellipses).

As it stands, you've done a solid job with shifting your ellipse degrees, and in patiently and carefully building out all of the details in your rims. While these aren't necessarily hard to do, they do demand enough discipline to just throw an amount of time at the problem, and it easily separates out those who are willing to invest the time, and those who still just want to rush through. Fortunately with all the other repetitive challenges prior to this one, most students who hit this stage are indeed well trained to get the job done well, instead of just fast.

The only thing I really have advice to offer with comes down to the tire treads. Some tire treads are relatively simple and subtle with minimal raised areas, whereas others have larger, chunkier areas. Looking at your tire treads, for the most part it does appear that you may have somewhat forgotten about the principles covered back in lesson 2's texture section - specifically the idea of all textures being implied through cast shadow shapes, rather than actually being explicitly drawn using line.

That said, I can see that an amount of that did sink into your general approach to drawing, as there were definitely areas where you worked elements of those concepts into your drawing - for example in wheel 22 where you tried to avoid outlining each tire tread form fully, opting instead to have lots of broken lines where the eye could flow through more seamlessly. That said, we're still dealing with lines here, and in many cases you're still drawing those textural forms themselves - going so far as to define the internal edges of those forms.

Here's a comparison of different approaches to this kind of problem that should help. Specifically focus on the right side, where the box form itself has absolutely no internal details. Where the silhouette sticks out along the top, we capture it with line, but everywhere else we're just focusing on the use of that cast shadow to imply the presence and nature of that form. More importantly, the cast shadow actually defines the relationship between that form and the surface upon which the shadow is cast - something we don't get in the technique on the left, or in the ways you employed in your wheels.

Now, my hat's off to you for the sheer patience and care with which you drew each and every tire tread in its entirety. That discipline and patience will serve you well - but it won't always be required of you in quite this way. Texture is a matter of communication - we're conveying the information the viewer needs to understand what it might feel like to run their fingers over that object's surface. In order to achieve this, we don't need to hammer it out so fully in every possible area - just enough to suggest it in key places, and blending into a much sparser texture everywhere else to provide areas of rest. The dichotomy of rest areas vs. areas of interest will also serve a purpose when it comes to design, where going fully detailed can actually be a problem, rather than just a tiresome task, specifically when it creates too much visual noise and becomes distracting. I don't think that really happened here, but it is definitely a risk when we get into drawings that contain more than just these individual wheels.

Anyways! I'm primarily nitpicking on a fairly minor aspect - as a whole you're doing a great job, and I'm happy to mark this challenge as complete.