Ultimately we do have to work within the limitations of our tools - so, if we need a certain degree, we can only really pick the one closest to it in our template. And, if we have several ellipses, each requiring a different degree, and the closest to it is the same degree on the template... well, that's simply all we can do. Long term we are working to provide students with access to far more comprehensive ellipse guides than the master templates (I've purchased a laser cutter for the guy who handles the pen sales, and he's working through some tests as we figure out how to provide as many degrees/sizes as we can manage while staying within a $30-ish range), but for the time being, the master template simply has to do. Fortunately, there is one area in Lesson 7 in which being able to produce consistent ellipses is quite important, but where the master ellipse template will do just fine, so you won't have to worry too much about that going forward.

And, as far as this challenge goes, despite those limitations you've still done a great job. Starting with the structural elements here, you've constructed your wheels with consideration both to the little "bump" that occurs in the mid-section, making the tire appear more inflated and bouncy (and suggesting that it's full of air rather than just solid). You've also been quite fastidious in establishing the side edges of the spokes on your rims, rather than only focusing on the "face" of it. In so doing, you've helped to really increase the general impression of solidity.

The other part of the challenge is texture - that is, the texture of the tire treads themselves. It's fairly common for students to, as a result of this challenge being very far removed from the last time we talked about texture in lesson 2, end up forgetting about the difference between explicit and implicit markmaking. So, this challenge becomes something of a "trap", giving them a little reminder that they should probably review that material before they complete the course as a whole.

It seems you did not come out of that trap unscathed - you do frequently, especially when dealing with the "chunkier" tire treads, deal with outlining each individual textural form in its entirety. As you'll note in Lesson 2, textural forms should not be drawn directly, but rather they should be implied. In drawing the shadows that those forms cast, we're able to make those shadows small and slight, or big and broad, depending on how we choose to have the lighting impact the object. You can think of it how on a sun dial, you'll have very small shadows at high noon, and very long shadows at dawn and dusk, when the sun is very low on the horizon.

You can also see this concept demonstrated here on this example of african bush viper scales. It's not a tire, but it's still very much the same.

The reason this is important is that when we have wheels floating loosely in space, we can pack them full of contrast and complexity and it won't matter. But if we have such a wheel as part of a larger vehicle construction, all of that detail packed into the tires is going to immediately become a focal point, drawing the viewer's attention if you want it to or not. Working implicitly, using only these specifically designed cast shadow shapes, allow us to control how much attention we want that texture to draw, without changing the nature of the texture itself. We provide the viewer with enough information to fill in the rest.

Above all else, keep in mind that working implicitly does not mean drawing the shadows you see in your reference. Rather, it's about understanding the nature of each textural form, how it sits in space and how it relates to the surfaces around it, and then creating a shadow based on the lighting situation you desire. You can read more about this here.

And that about covers it! I won't be holding you back - again, the challenge is more of a little reminder for students to review that Lesson 2 material. I'm confident you can do so on your own, so I'll go ahead and mark this challenge as complete.