There's a company up here (brisbane) that sells just the outer bands... (Race engineering)
Can get 8 or 10 inch wide in a 15. Think the widest you can get in a 14 is 8.
Just gota find some wheels with the right sized ceters to remove and weld into the new bands...
Either way they buy the bands off of ROH so you should be able to get them anywhere really..