While this challenge is certainly not an easy one, as a whole you've done very well. When it comes to construction, I can see that you certainly made the most out of your ellipse guide, and while this did force you to work quite small, you've handled it quite effectively. You included a lovely little widening through the midsection of your wheels, which helps promote a sort of "inflated" look to the tire, like something that has a bit of give to it rather than being entirely dense and unyielding. You've also, despite the very limited space, done a great job of paying attention to the side planes of your spokes and other structures, ensuring that they do not merely appear paper-thin, but rather have a good bit of thickness to them, helping to contribute to the overall illusion of solidity.

When it comes to the texture portion of the challenge, you certainly sidestepped the bear trap I set out, and demonstrated a very strong recollection of the concepts discussed back in Lesson 2. I think this stands out most of all in number 12, which is a particularly tricky one, but also where it is most obvious that you're thinking not about drawing on the surfaces of a given textural form, but rather defining the shadow it casts, separately from itself, upon the surfaces around it.

One of the important things, when it comes down to texture, really is about approaching designing our shadows in a two step process, first outlining and designing a given shape with intent, considering how that shape establishes the relationship between the form casting it and the surface receiving it - unfortunately this would no doubt have been extremely difficult to manage given the smaller size of these wheels, and thus the even smaller size of the shadows themselves. So, I can see that much of the time you did likely "paint" those shadows on stroke by stroke - but all the same, you've demonstrated a great deal of control and care here, reflecting the fact that you were most certainly considering those relationships between the forms and surfaces, rather than just painting one stroke at a time and hoping for a more general, vague "impression" of the texture you were after.

I do however have one suggestion, in terms of something to consider. A lot of these tires have fairly shallow, groove-based tread patterns, and this can often make it a lot easier to get away with explicit markmaking. That in and of itself is not a problem - in fact, I work that way in the demonstration as well. That said, it is important that we continue to think about textural forms and the shadows they cast, as we put our marks down, as there are definitely cases where the subtle impact of thinking in a certain way can make a difference. One such case is 17, where it appears that you've filled in the more considerable grooves running around the tire.

This is an example of a case where a lot of the focus is on the grooves themselves - which are negative space - similar to the holes we might encounter in spongy textures. In this case, we may feel inclined to simply fill in the negative space, focusing only on the groove itself as the textural form - but this is incorrect. Rather, the textural form becomes the walls surrounding the groove or hole, which cast shadows upon each other, and upon the floor of that negative space. This diagram helps to explain the concept. Basically, we still have to be thinking about the relationships between the different structural elements, even if they're so small that at the end of the day we're still going to draw a one-off stroke to represent a given shadow, and it ends up filling in the whole space. How we think about a problem influences a lot of the subtler aspects of how we draw its solution - and while these subtle points are not always discernible, ensuring that we continue to think about them will help us capture them in the cases where they're just barely noticeable, but make a significant impact as a result.

Just something to keep in mind. As a whole, you've done an excellent job here, so I'll go ahead and mark this challenge as complete. Keep up the good work.

Hold up, is that a wheel of CHEESE?! CHEESE HAS LITTLE HOLES AND IRREGULAR SURFACES. CHEESE HAS TEXTURE. THIS IS NO CHEESE, THIS IS MERELY A BLOCK OF STONE. GET OUT. LEAVE FOREVER!