Generally when critiquing this challenge, I do so in two separate steps, first looking at the constructional elements of your wheels, and then looking at how you've handled the texture of each tire's treads.

Starting with the structure, you've handled this quite well overall. I can see that you're fairly attentive to ensuring that you're not simply drawing the front face of the rims/hub cap, but also including the side planes of those structures, to ensure that they feel solid and three dimensional. Looking at the structure of the wheels themselves, I noticed a greater tendency through the first half or so to draw fairly straight cylindrical structures for your wheels, which often made them appear quite a bit more stiff. Beyond that point, starting at 11 or so, you leaned more into making the wheels get wider through the midsection, creating a sort of "bump" which did a great job of capturing the sense that the tire itself was inflated, reducing that stiffness and making them more believable in terms of what they were meant to represent.

Your question about evenly distributing those details technically pertains to both sections of the challenge - structure and texture - but in each category the question applies to a different sort of problem. For this section, unfortunately I don't really have a satisfactory answer to provide. The problem comes down to how we can identify specific degree positions on a circle in perspective, and the honest answer is that I don't actually know. I suspect that we could, to a point, enclose the inner circle of the wheel in a plane, and then with the assumption that the plane itself would represent a square (since it's encompassing a circle in 3D space, which we can assert merely because the wheels are floating in the void and do not need to remain consistent with any other objects), we could subdivide that plane to give us the 0, 90, 180, 270 degree positions from the horizontal and vertical cuts, and then the 45, 135, 225, 315 degree positions from the diagonals... I think. But this is all goes into technical perspective of which I cannot claim to be an expert, or even especially knowledgeable. For the most part, I do this sort of thing by eye, although it is even then quite challenging.

Moving onto the second part of the challenge - texture - we look at how you've actually tackled the tire tread patterns themselves, specifically in terms of how closely you've held to the principles espoused back in Lesson 2 about explicit vs implicit markmaking. Shallower groove-based patterns are generally quite forgiving, but we can see how you've attempted to handle them more prominently when the textural forms themselves get bigger.

Overall, you've actually done a pretty good job with this. 12 stands out as a clear attempt to work with cast shadows and avoid explicit markmaking entirely. We can also see examples of this in the smaller wheels you did with your ellipse guide. As a whole, it's clear that you made a concerted effort to apply those principles - something that is actually not as common as you'd expect. This challenge itself exists as a sort of trap to painfully remind students to review that texture material before they finish the course.

As to your question, here I think that the matter of distributing our textural forms evenly comes down to the fact that:

Without being able to put down any explicit marks, how can we hope to maintain enough information in our own minds to keep the distribution even?

And that's an entirely fair question to ask. While I'd love to say that our brains are limitless in their potential, it's more fair to say that there are little tricks we can employ. For example, where a whole line would be way too much and would entirely contaminate the drawing, a single point would be far less costly, and would most likely end up being engulfed by another mark or a shadow later on anyway. In fact, we already apply this principle with the ghosting method.

So, while we can't plot everything out in explicit detail, we can leave ourselves little markers to show how we've laid that spacing out thus far, so as to make eyeballing it (since that's all I know how to do) more reliable.

Anyway, that about covers it! All in all, solid work. I'll go ahead and mark this challenge as complete.