as mentioned above, think the easiest way would be to have a wheel section, then a seperate topic for each wheel type, then as many pics as poss posted up by users of their car with that wheel on it (could also post up where they bought them from and for how much?? as a xomparison sort of thing??)....
Not sure how best way to seperate mk1,2,3,4 and 5 though?? child boards in each model section, or just state on topic title which model for??