it is 320mm but the hole centers on the x challenge hub is 120mm and the hole centers on the cast rim are smaller. not sure on the hole centers on the cast wheels i will check tomorrow. unless i had a brain dead moment when i offered it up but i will check it again to make sure.
Did he say it was a straight fit? I haven't found anything as of yet but it's on the list of many things i need to get done. It would be nice if there was a list of all rotors,wheel spacing and offset.