Starting with the structural aspect of the challenge, overall you're doing pretty well - you're using your various ellipses to establish a profile for each wheel that features a slight arc to it, helping to make the tires appear more inflated, as though the whole wheel would land with a bounce rather than a solid thunk.

One thing I did notice is that when it comes to establishing how the spokes of your rims connect to the inner surfaces of the rim structure itself (I imagine that's pretty confusing, I'll show you what I mean in a moment), you are at times inconsistent in terms of where the side planes of the spoke structures themselves start and end. For example, as shown here there are some cases where you had the side plane continue much farther along, going past where it would have intersected with the inner surface of the rim. You did this more correctly in most cases, but I also noticed some areas where those structures felt less solid - for example, here. That decrease in solidity came from the fact that you executed the mark two separate but connected edges with a single stroke, instead of breaking it into two separate marks as insisted upon in the principles of markmaking from Lesson 1.

Continuing onto the textural aspect of the challenge, this is an area in which the exercise ends up being something of an intentional trap for students. Being as far removed from Lesson 2 and its textural concepts as we are, it's not entirely uncommon for students to forget what's written there about conveying textural forms through implicit markmaking rather than explicit markmaking where we outline each form in its entirety, drawing it via constructional means. This is a trap you've certainly fallen into, and while your tire textures still look pretty good in isolation, there are definitely a lot of cases where that density of visual detail will become a focal point. Meaning, when used as part of a larger drawing or construction, of a whole vehicle for instance, they're going to draw the viewer's eye straight to them, if you mean for it to or not.

Conversely, if you look at this example of african bush viper scales (which of course is not a tire, but the same principles apply), you can see how conveying the presence of each textural form using implicit markmaking - that is, by drawing the shadows they cast rather than outlining them and drawing them directly - allows us to control that visual density and exactly how heavy the use of ink ends up being. We can convey the same texture with minimal marks, or with a lot of them, allowing us to decide just how much attention those textures should draw from the viewer, without changing the nature of the texture being conveyed.

Worry not - these issues are expected, and I don't assign revisions for them. It simply helps to provide students with a more direct reminder that they may want to review material from previous lessons to refresh their memory, and to identify gaps in their warmups where certain kinds of concepts may have gone unpracticed, before they finish up the course. In this case, I'd strongly recommend that you review Lesson 2's texture section, with these sections in particular:

In addition, this diagram about handling textures with holes, cracks, and grooves, can also be quite helpful. There are a lot of tires with shallower grooves that students easily end up approaching incorrectly. In a texture featuring bumps, or bricks, or scales, or other such common physical elements, the things we actually ascribe words to are the forms themselves. A bump is made up of a form, a brick is made up of a form, and so on. In this case however, with grooves, cracks, and holes, the thing we've named is an absence of form - but without considering that, we still end up trying to draw those named things directly. The diagram explains why this is incorrect, and why when dealing with grooved tires, we actually want to be thinking about the walls around the grooves, and how they cast shadows upon one another.

The last thing I wanted to call out is similar to the issue I called out involving your spokes. As shown here, there a number of cases where the side plane of the walls enclosing those grooves were not defined correctly.

Anyway, I'll leave you to review the concepts I've mentioned here, and will otherwise go ahead and mark this challenge as complete.