Alrighty - so because you were unable to work with an ellipse guide (which I still highly recommend for these last couple lessons), I'm not going to comment on the ellipses beyond saying that you definitely need to continue practicing them quite a bit. This is normal - hence the ellipse guide option - because ellipses are tricky to master, and are expected to take a good deal more purposeful practice in your warmups.

Moving forward, there are a few things I want to draw your attention to with these wheel constructions. Firstly, when drawing the rims on the side of the wheels, remember that these are three dimensional forms - don't just focus on drawing the shape of the side, but also distinguish the fact that these forms have different planes. We don't want these rims feeling like they're paper-thin because they haven't been given any thickness.

Looking at your tire treads, remember that these constitute a texture - they're made up of little forms present along the surface of the tire, and so this is the sort of thing we discussed back in lesson 2. All textures must be captured as a series of cast shadow shapes, not as lines. You definitely forgot about this. One point that can help us avoid making this mistake is to make the point of drawing each textural mark using this two-step process. This will force you to think of how every mark is a shape, which in turn can help you think about how each shape is the shadow cast by a particular form.

Now, these wheels have a lot of room for improvement, but this challenge isn't about making you drill wheels until they're perfect - it serves more as a reminder of some of these concepts, and perhaps as a way to emphasize just how helpful it is to get your hands on an ellipse template if you can. In Lesson 7 it becomes even more important, as we use ellipses to create squares in 3D space, and build grids in which to place our vehicles.

So, be sure to keep the points I've raised here in mind, but I will go ahead and mark this challenge as complete.