Overall, very nice work! I do have a few things to call out, but as a whole you've done a solid job with the construction of your wheels. You've also paid a good deal of attention to the construction of the rims, and tackled everything with a good deal of care and patience.

The first thing I want to address is the choice of setting your ellipse guide aside. I do understand that the more affordable ellipse guide solutions are small, but the reason I push students to use them here is so we can eliminate ellipses as a point of difficulty and focus instead on the core of this exercise in particular. Students are expected to still need plenty of practice with their ellipses and cylinders past this point, but we have already introduced exercises in which you can do this. After all, you're still meant to be practicing them as part of your regular warmups, and so there is no need to also have your wheels double up as ellipse practice. Instead, in every exercise, we're trying to drill down and focus as much as we can on specific concepts.

That said, your wheel constructions are, as I mentioned, still well done. The free hand ones get visibly uneven, but the methodology applied - specifically where you're placing your ellipses - is coming aling well. I am however noticing an amount of sketchy/scratchy linework in areas other than the ellipses, like in the rims of #19 for example, that suggests the fact that you've approached the base wheel construction in that matter (instead of using an ellipse guide), it's impacted the integrity of your linework in general. This is a common result - when we draw using rulers and ellipse guides for certain parts, we're also encouraged to keep our other linework clean and purposeful, using the ghosting method even when freehanding. When however we open the door to sketchier linework for our ellipses, even if to compensate for the lack of an ellipse guide that is big enough, it tends to impact how we approach the rest of the drawing as well.

To that point, I'm also noticing something of a distinction in your drawing between a fainter "underdrawing" when freehanding, and then lines that go back over to darken and commit your linework by tracing. As a whole, while the constructions come out reasonably well, the linework itself largely suffers across the board.

The last point I wanted to discuss were the tire treads. Overall you're doing a pretty good job of this, but there are some cases - like #5 - where you opted to construct each chunk of tire tread, rather than implying their presence using cast shadow shapes (as discussed back in lesson 2). This is primarily more relevant when we get into these chunkier treads, but all the same, it is a texture - and so textural techniques should be used. Additionally, you may want to use a fineliner or brush pen to fill in cast shadow shapes instead of filling them in with your ballpoint, just to keep the blacks solid.

So! All in all, you're doing a good job, but you do have a few things to keep in mind. When tackling your vehicle drawings in the next lesson, please be sure to use your ellipse guide wherever possible.

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