Originally Posted by
Karl @ FPT
Depending on the size of your wheels and what they are I'd go 300mm ST/Mondeo setup at eh front and leave the back as they are.
I have come to the same conclusion
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However, I have to ask why you would choose the Mondeo MkIII calipers over the Sierra items. I agree that they seem a little lighter but to limit your choice of wheels less does seem annoying.
It was probably the main reason I went with the Cossie 4WD items ; almost nothing fits behind the S1 wheels
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Back to the OP AFAIK the ST170 discs fit with the MkIII Mondeo calipers but the hubs require redrilling and rethreading to take the larger bolts. I have not heard of the ST170 calipers fitting before. I understand that with the Mondeo/ST setup some 15" wheels may fit with the caliper being massaged but 16" is the smallest wheel that can generally fit without any issues.