Hey goodboy! Im glad you are prepared to get roasted, cause I aint holding back :)

I think that as a whole you are doing good job on this challenge, regarding the solidity of your wheels, they are indeed solid, and I specially like that you are making the most of your ellipse guide- You are not only using it to mark each side, but also you are capturing the subtle inflation and compression by adding several ellipses in the middle, which you are then taking advantage when drawing the tire treads.

Regarding the purpose of this challenge, Uncomfy kind of sets a trap here- By this stage, students have basically forgotten about the principles of implicit textures presented on lesson 2, so instead of takling the tire treads that way, instead people try different explicit and constructional approaches. To be honest, its completely our fault that we blindly trust the same man that made us draw 250 boxes.

Taking all this into account, it seems like you started doing a explicit approach, like your second wheel (sorry for mentioning that one, but I told you I aint holding back), but then by your forth you started to make the shift, and your sixth I like you started being more bold with it. However, regarding this one in particular, while it shows that you are trying to go on the implicit path, you are not using cast shadows, but form shadows, I recommend to go back to this video that differenciates the two, and also its advised to go back to that section of the course to refresh our memory on all this. I think that your 10th weel is going on the right direction since it seems like you are using cast shadows.

On the ones that have more subtle grooves, like 4, 8 and 11, its not that noticible, its more on the chunkier trims where this is seen. Like in your 20 you are really doing the right thing, though some of those cast shadows are a little rough, i know how hard just drawing the cast shadows is when all you have been thinking this past lessons is implicitly constructing different objects, but a good approach is this one, while this is perfectly applyable to the more shallow textured wheels we first talked about, a similar approach could be made to those with bigger trims, were you first mark down the contours of the shape that the cast shadow is forming, and then filling it up. Again, this is pretty tough, but you are heading on the right direction.

Now I want to go back to the more constructional part of this challenge, I honestly think you did a good job taking into account that you just had one degree for your ellipses, while in some of your wheels I get this sense of stifness, Im not really worried since I have been reviewing your work for a while now and I know for sure that you know how the degrees change in a cylinder. This said, you did some really cool stuff with that ellipse guide, I specially like the inner part of your first wheel and also the inner part of the number 16.

As I said, you did a good job on this challenge, so Im going to go ahead and mark it as completed! Keep up the good work and good look on the final stretch.