Starting with the construction of your wheels, I think you took a great deal of care to draw as many ellipses as necessary to construct your wheels, you've done a good job of capturing the gentle swell through the midsection of your wheels to give them a nice inflated look where appropriate, and I can also see you were drawing the far side ellipse with a slightly larger degree than the nearside one, great work. In some cases, such as 19 and 22, your ellipses aren't really aligned to the minor axis that you drew but on the whole you've done a remarkably good job with them, considering these appear to be freehanded.

On that note, I really would advise picking up a master ellipse template (there's one linked in the recommended tools section on the DAB website) to make your life easier when going through lesson 7. It's completely understandable that not all students can get their hands on ellipse guides, in which case freehanding is really the only option - but sometimes students choose to freehand them thinking that doing so will make the exercise more effective.

Just in case you're in the latter group, I do want to reiterate that we recommend the use of certain tools in certain circumstances to reduce the number of problems the student has to face all at once. This allows them to focus more strictly on the specific issues at hand, making the exercise more effective. If you did try getting an ellipse guide but found that full sets are too expensive (they can definitely get quite pricey), most students actually use the more limited "master ellipse guides" which provide a range of degrees but only go as big as maybe 1.5". Despite this, they are still very useful for this challenge and throughout Lesson 7, and are worth picking up - and of course they're much more affordable than a whole set.

I think you have done a good job constructing the rims of your wheels, carefully spacing the spokes as evenly as you could, and observing your reference to capture the individual qualities of each wheel. There are a few cases where it looks like you have filled in the negative shapes between the spokes with black, and it is a little unclear whether you're describing cast shadows or just filling in the gaps. If you look at 24 and 25, 25 appears to be much more mindful with your shadow shapes, it is clear here that you drew the cast shadows, and it conveys much more information not only about the spokes themselves, but the interior of the wheel where the shadows are being cast onto, good work.

Moving on to the tyre treads and textural work, here you seem to have explored a few different methods. Some of the wheels, mostly on the first page and also number 13 you have explicitly outlined every bump on the tyre, and while you've done it well, it's not really what Comfy is aiming for, I think, he is looking for students to employ the techniques taught in the texture section of hesson 2 here. Some of your wheels I think you have done a good job drawing the tyre tread implicitly (like 20 and 25) only working with the cast shadow shapes and bumps that affect the sillhouette.

At the end of the day, the textural techniques shared in Lesson 2 are important because of the control they give us. On the wheels where you were drawing explicitly, you were by and large forced to capture all of the different details of each tire tread, in their entirety, covering the whole tire. As shown in this example however https://imgur.com/qWwH4tc (which isn't of a tire - they're actually african bush viper scales), capturing texture through implicit means allows us to control exactly how much ink and how much contrast will go into a certain section of a larger drawing.

After all, in this challenge you're working with individual wheels - but if you're drawing a whole scene, being forced to include all of the tire texture into a tiny section will result in a very high contrast, very eye-catching section. It'll result in a focal point where you do not mean to include one, which in turn will mess with your ability to control your composition and the way the viewer's eye navigates through it.

Anyway, the texture "trap" is something many students fall into. It's not something to assign revisions over, and as a whole I think you're still doing very well. It's just a bit of a reminder, so keep it in mind as you move forwards. Feel free to move onto lesson 7.