When facing the frustration of adding details to the smaller wheels, you were at something of a crossroads. You could choose to see the issue as being the scale of the wheels themselves, that they had to be larger in order for you to successfully apply that detailing, or you could opt to alter how you approached drawing those details.

The reason the choice you made was the lesser of the two was because you forgot that the details you're drawing here are textures, and as explored way back in lesson 2, texture - specifically with the implicit drawing techniques we're meant to use in capturing it - is very flexible, and can change in order to suit the contexts in which it's being drawn.

What you used here throughout all your wheels were explicit drawing techniques - you defined each and every textural form, every bit of tire tread and so on, outlining them and constructing them in their entirety. It's a mistake students often make in this challenge, and it's an excellent opportunity to remind students of what they're forgetting.

Now, all that aside, you did do a pretty good job. Your wheel constructions suffered considerably when you jumped from the ellipse guide into freehand wheels, but you started to claw your way back steadily as you went along. You definitely still had some wobblers like 19 and 20, but there were definitely some, like 25, where it honestly looks close to being done with an ellipse guide.

You've also done a good job of building out the rims of your wheels in many of these, like 17 and 25, and as a whole there's a lot of improvement. It's the texture aspect - specifically the fact that you didn't really delve into cast shadow shapes at all to imply these tire treads, and when you did get into shadows (like in number 9) you opted to fill in the side planes of your tread forms rather than drawing the shadows they cast. As shown here, we're able to convey a lot more information to the viewer about the relationship between the tread form and the surfaces around it by drawing the cast shadow, rather than simply shading in one side of the form.

Anyway, as I mentioned before, it's a common mistake to make, and a rather valuable one too. So, I'll go ahead and mark this challenge as complete. Be sure to pull your ellipse guide out in the next lesson, as the precision and accuracy it will offer you will be extremely useful.