Yes, you should attempt to fill in the outer rim, and yes you should model the axle hole.
It doesn't seem too difficult to see the profile of the groove by prising up the rubber tyre, as it is not glued on. But I can understand if you don't want to do that. The matching inside of the tyre has the same profile, and should also be modeled as a closed surface.
This is what the profile looks like to me:
2 0 -8 0 -32 -6 0 -32
2 0 -6 0 -32 -2 0 -28
2 0 -2 0 -28 -2 0 -26
2 0 -2 0 -26 2 0 -26
2 0 2 0 -26 2 0 -28
2 0 2 0 -28 6 0 -32
2 0 6 0 -32 8 0 -32
Thanks for continuing to work on this.
It doesn't seem too difficult to see the profile of the groove by prising up the rubber tyre, as it is not glued on. But I can understand if you don't want to do that. The matching inside of the tyre has the same profile, and should also be modeled as a closed surface.
This is what the profile looks like to me:
2 0 -8 0 -32 -6 0 -32
2 0 -6 0 -32 -2 0 -28
2 0 -2 0 -28 -2 0 -26
2 0 -2 0 -26 2 0 -26
2 0 2 0 -26 2 0 -28
2 0 2 0 -28 6 0 -32
2 0 6 0 -32 8 0 -32
Thanks for continuing to work on this.
Chris (LDraw Parts Library Admin)