I think someone on here, if not more than one, is or has run those tires before/now.
Here is a link about that. I also read some more about no on seeing 255s on 18s, but doesn't mean it hasn't been done.
http://www.grandprix.net/ubb/ultimatebb.php?ubb=get_topic;f=1;t=002259#000001
_________________________
2002