Looks good! Maybe you should not use Spheres in the Wheels, instead utilize Textures for that Part and save some dozen Tris.
Trying something...

Well this way the Image works here - not shure if it works for you too since my Browser suppresses the Referrer.
Trying something...

Well this way the Image works here - not shure if it works for you too since my Browser suppresses the Referrer.