Thanks for the kind comments and tips!
I've got some dollar store pastels lying around that I'll try to lighten / blend the tires with.
The camo scheme was done by masking. I used the kit paint instructions for reference but it's not traced curve for curve, just eye balled for basic shape and size. The mask was made of lots of short strips of tape with random curves cut out of them that were arranged through a bit of trial and error to avoid sharp angles. Definately not the most efficient method but it was kind of relaxing and I got into a grove doing it while watching you tube videos.