well what i did was...
1. make a duplicate layer of the car
2. use circle selectioon, and select around one of the wheels, then select>inverse
3. erase all around the wheel, not too close to the other one tho...
4. do the same to the otherwheel
5. now you have a layer with just the wheels ontop of the car.
6. use the selection tool(magic wand) and delete the spaces between spokes, try to get as much as possible without taking the white part out.
7. then take the eraser and make a small brush and zoom in real clos
8. erase the lugs and center cap if they arent the same color, and you dont want them colored later.
9. you now have a layer with ONLY the white parts of the wheel.
10. i always desaturate at this point,
11. adjust colors as you want...