-- been in business for 15 years, not going anywhere anytime soon so my character means a lot to me-this is my personal kit for my personal race car that just won't work out - i bought them on a hunch they would work and they won't fit within my required class ruleset for wheels
from what i learned on test fitting them behind the 15x7" wheels I have on hand (15x7, +35 Te37 and 15x7 +42 Team Dynamics) you will need to run a wheel like the new gen 15x8 TE37 (+32, +35) offerings or a Gram Light 15x8 perhaps and then add a 8-10mm spacer on top of that and you should be good to go if you are working on fitting them behind 15" wheels. If you can go bigger they will do well behind sizes like 16x8 or 17x7.5
I specifically wanted the AP CP8350 caliper as I have used them on cars in the past with great success but just won't work for this particular application.