Simple printable wheels for N10/N20/N30 Motors (3mm D-shaft)

What do you do when you need wheels, but ordering them will take too long? you print 'em yourself - I had a look around, and the ones I could find had too large d-holes, so I decided to make my own.

Print the actual wheel in some stiff material (PLA works), 
and the tire in TPU.

The tire isn't optimal grip-wise, so if you come up with something better, let me know.