Very nice work! Starting with your wheel constructions, I'm very pleased with how you've approached building out the structure of each individual one. You've made excellent use of your ellipse guide to lay down all the necessary cross-sectional slices along the length of each given cylinder - the use of additional ellipses on either end, and a larger one towards the middle has gone a long way to help you achieve that impression of an "inflated" tire, rather than just a solid, unyielding tube.

I'm also very pleased with the attention to your rims/hubcaps. You've got a variety of designs here, and it's clear that you've put a good deal of time into analyzing their spoke arrangements and other features. Additionally, working at this more limited scale (as a result of the ellipse guides) can definitely be tricky when dropping in tighter detail like that, but you've done quite well. One thing that can help to push those kinds of smaller details further is to rely less on explicit markmaking (like outlining each individual structure), and to fall back to textural principles, using cast shadow shapes to imply the presence of certain forms. When we start to get into more dense markmaking, concentrating in tighter areas with more detail, the strengths of implicit markmaking definitely come into play (even when not working with something that falls so strictly into the category of texture).

Now, I can see that you have played to varying degrees with the use of these textural principles when tackling your tire treads - which themselves are more obviously textures, being that they're made up of little rubber chunks or grooves arranged across the surface of a larger form. This is always one of those tricky things that trips students up here - while you clearly remembered the points raised back in Lesson 2, many students will be far enough removed from that lesson that they fall back to strictly explicit markmaking.

This mainly comes up when we look at the "chunkier" tire treads. In your case, you did fall back to the use of explicit edges/outlining, but it was clearly in a way where you were trying to think about just how you could leverage implicit shadow shapes most effectively. I found this tire tread to be a particularly interesting attempt. You outlined the distinction between the top and side planes of your tread chunks here,

The fact that you were trying to think about the tread chunks in terms of being 3 dimensional structures with distinct top and side planes is very important here - though it is necessary to take it a step farther by holding those planar distinctions in our minds, rather than drawing them right on the page. In thinking about where those planes are, we can better understand when we'll see one side as opposed to another. If you look at what I drew on top of that one, the tread chunks along the bottom side of the wheel switch to showing us their "upper" side plane, rather than the "lower" one we were seeing along the top of the wheel.

In thinking about this, in relation to wherever we place our light source, we can think about which forms would cast shadows that would be visible to us. Another example I like to share in regards to this is this bush viper scale study. While it's obviously not a tire texture, the nature of the texture actually results in a lot of very similar challenges being tackled. Of having to understand how each scale sits in space, and how to use that information to determine what kinds of shadows will be cast, and where.

Anyway! All in all I'm very pleased with your work here. There is of course continued room for growth in the use of textures, but I'm pleased to see that you were exploring the different ways in which textural principles could be applied here, rather than just falling back to strictly explicit markmaking for everything.

I'll go ahead and mark this challenge as complete.