Hahaha, very fair - I wouldn't enjoy freehanding them either. At this stage, while students have had a fair bit of mileage with ellipses, it's really hard to overstate just how tricky they can be. There are plenty of cases where it's not a big deal - an ellipse being a little wonky may not really impact much, but with wheels, they constitute the core structure of the object, and so having them be off by a small margin can definitely make things a lot trickier. So! I'm glad that while you did play around with some freehanded ones, you did largely stick to your ellipse guides.

So, getting into the constructional side of your wheels first, by and large you've done a good job - you've used your ellipse guide well to flesh out the structure for the most part, you've been mindful of not only the outward face of your rims, but also their side planes in order to ensure that they feel solid and structural. There were a couple things I noticed that I did want to call out though:

• Avoid going back over your linework without a good reason for it. There are a few places we can see this to varying degrees - for example, on this wagon wheel the internal edge of the wheel portion itself is really dark. There are many possibilities as to why - perhaps you made a mistake and just wanted to cover it up, perhaps you wanted to capture that slightly darker rim (which would be a local/surface colour so still something we should leave out for our drawings in this course), or something else. But in general, the result is that this really thick internal edge kind of breaks the cohesiveness of the overall structure. Try and avoid any really thick areas. Even when you're adding line weight, focus it in limited, localized areas to help clarify how different forms overlap one another, as shown here. We can see similar issues in this one, though I think it's a bit more clear that you're trying to either capture the local surface colour you see in the reference, or differentiating the different surfaces by filling in one, which is more similar to form shading (which as discussed here in Lesson 2 should be avoided).

• If we take a look at this one, we can note that the wheel you've drawn follows the structure of a fairly straight cylinder, but the wheel in the reference actually gets a bit bigger through the midsection. This is actually important - it lends itself to a more "inflated" look, making it feel like it'll absorb an impact better, and generally be less stiff and rigid. You may have avoided that in this situation because of the ellipse guide limitations, but if it was simply an oversight, I did want to call it out.

Continuing onto the tire treads themselves, this is where the challenge becomes a bit of a trap. We are pretty far removed from Lesson 2, so students at this stage have a tendency to forget everything we discussed there about conveying textural forms through implicit markmaking - implying their presence by drawing the shadows they cast on their surroundings. Tire treads however are an excellent example of textures, given that they're an arrangement of forms following the larger cylindrical structure, and so we should be employing implicit markmaking here instead of explicit outlines.

It may look fairly normal in these wheels, what with them floating in a void on their own, but as soon as we use them in an actual vehicle, the concentration of detail/linework/contrast will create a focal area that'll draw the viewer's eye to your wheels, whether you want them to or not. Textural techniques however allow us to control the kinds and quantity of marks we put down without necessarily changing the nature of what's being conveyed. For example, if you take a look at this african bush viper scale texture, the number of scales does not change, even though in one case the shadows are much broader, and in the other they've shrunk down.

Another point worth mentioning is that when we deal with grooves in our tread texture, it's actually not as bad to work explicitly - but the way in which we actually think about the textural forms themselves are still what matters most. Reason being, students have a tendency to try and think of the grooves themselves - which are like holes, or void/empty spaces as the textural forms, but they're not. Instead, it's the structure around them - the walls, and the floors - that we need to consider. You can read more about that in this diagram.

Now, while you did fall into the "trap" of the challenge, that is largely expected. It's just a reminder that you will want to review the material from Lesson 2, and refresh your memory on all that it entails. That said, I'll leave you to that, and mark this challenge as complete.