On this model i used 2 method one is to bake NM from a high poly mesh and other method with Photoshop! Like for example, the track's normal map are drawn in Photoshop and converting it using Nvidia NM tools or nDo2.
Many 3d artist when they are modeling a shape they use HP shape to bake the Normals... Thats all good but IMO sometime it is a waste of time. you can use PS to bake details and still make them look realistic.
Thanks! I will be posting some of my texture workflow... Well you need to look for better textures/reference, if you have any questions about textures you can send me a note, ill be glad to help you with some tips