Originally Posted by xbox73

Though I don't have the kit, so therefore don't have any personal experience & can't vouch for the accuracy, the following 2 links might help.

SSBC's own web page states "Minimum wheel size: ST", and I would assume "ST" is supposed to imply 'stock'?:
SSBC:: A193-1

This page states "Minimum Wheel Size Stock":
SSBC Quick Change Aluminum Brake Caliper Upgrade Kit A193-1