You may wish to call Bob Sage at Wheel Smith. 1601 W. Commerce Street, Corona CA 92808, USA. Tech line (951) 898-4563 / Order line (800) 854-8937 / Fax (951) (951) 340-0562. They have all of the centers and make all sizes including 18". Very good work and they will do the job on time. The Wonderful One