So it's actually pretty common for students to forget all about the texture stuff. It's one of the big reasons I have this challenge right here before Lesson 7, to make sure that students who've forgotten about the importance of capturing texture with cast shadows are given a quick smack on the wrist, and a thorough reminder. That said, while you break the texture rules in some places, you're actually doing better than most at making clear attempts to apply those principles.

The biggest one that stands out is 21, where you're clearly working without outlining your textural forms, and instead planning out and filling nice, purposeful shadow shapes. From what I can see, it does seem like you're filling in the side plane of those big "chunky" treads - it's better instead to focus on the shadow that is cast, as shown here, because doing so allows us to not only establish how the textural form exists in 3D space (through its silhouette), but it also gives us a sense of how that textural form relates to the surfaces around it.

With shallower, less chunky tire tread - like 19 - this is less of a concern, and I think the way you handled the texture there is looking great. Of course, on the flipside, there are cases like 20 where you relied on outlining elements too much, (24 also has more outline than it ought to), but all in all you're headed in the right direction and demonstrate an awareness, if not a clear grasp of how to apply those concepts.

Looking at your constructions, I am ultimately glad that you stuck with the ellipse guide. The issues you struggled with are pretty normal - short of dropping a hundred dollars on a full set of ellipse guides, students will generally just work within those limitations. That said, your very first wheel, which obviously was freehanded, actually came out pretty well considering the additional challenge involved.

So, you're handling the constructions well - your choice of ellipses for each side of the cylindrical form, placing intermediary ellipses in between, and your approach to pin down this variety of complex rims, it's all coming along great. So, I'll go ahead and mark this challenge as complete. Keep up the great work.